Rishi Sunak says Britain’s position on a Ukrainian peace deal has not changed, after reports emerged that foreign secretary David Cameron spoke to Donald Trump about the prospect of an agreement with Russia.

Lord Cameron met with Mr Trump in April at his Mar-a-Lago estate in an attempt to seek his cooperation to endorse more military aid for Ukraine.

According to The Sunday Times, Lord Cameron told the US presidential contender that fresh aid will help Ukraine hold its front lines and offered the Republican leader the “best possible conditions” to try and secure a deal between the warring sides.

He is said to have asked Mr Trump: “What are the best conditions in which you as president can make a deal in January? It’s both sides holding their lines and paying a price for that.”

The reports of Lord Cameron’s remarks are in sharp contrast with the official line long maintained by the Sunak administration, which states that the conditions for a peace deal are to be set by Ukraine and not agreed by other parties.

A spokesperson for Mr Sunak rejected the suggestion that the UK policy had shifted. “I don’t recognise those reports… our position has not changed. Putin must fail,” the spokesperson said yesterday.

The spokesperson added: “It is crucial, now more than ever in this conflict, that Putin is sent a very clear message that we will support Ukraine for as long as is necessary.”

Mr Sunak also said he has not seen the article carried by the Sunday Times but added: “… What I can tell you is that we have led when it comes to Ukraine.

“Investment in Ukraine’s security is investment in our security. Our Nato allies are already worried about the prospect of if Putin succeeds, that they’ll be next — with all the consequences that would bring,” he said.

Russian emergency services on Monday finished clearing the rubble in the region’s capital city of Belgorod, where a section of a residential building collapsed following what authorities said was Ukrainian shelling.

Fifteen bodies were pulled from the rubble, Belgorod regional Gov. Vyacheslav Gladkov said, and 27 other people were wounded.

Another three people in the city of Belgorod were killed by shelling late Sunday, he said.

Yevgeny Poddubny, a usually well-connected military correspondent for Russia’s state TV corporation VGTRK, said in a recent Telegram post that the Kharkiv assault marked the beginning of “a new phase.”

“We’re pushing the enemy back from the border, destroying the enemy in order to deprive the Kyiv regime of the opportunity to use relatively cheap rockets to attack Belgorod,” he said.

Ukraine’s commander in chief and its defence minister spoke to senior US officials last night as the two sides discussed the war-hit nation’s military aid and the frontline situation, Ukrainian commander Oleksander Syrskyi said.

He said the Ukrainian officials spoke to the US national security advisor Jake Sullivan, defence secretary Lloyd Austin and Charles Q Brown, chairman of the Joint Chiefs of Staff.

“We spoke about the situation at the front, as well the assistance that Ukraine needs on the battlefield,” the top commander wrote on his Telegram channel.

The call came as equipment and munitions began arriving in Ukraine from a $61bn aid package approved last month after months of delays owing to congressional wrangling.

Moscow’s forces have captured a number of villages and sent thousands of people fleeing their homes. They are trying to broaden the area of its most recent attack, which seemed to take Ukrainian forces by surprise and caused some to retreat from their lightly fortified positions.

The Independent spoke to a colonel from the Ukrainian general staff, who did not want to be named. He said: “The situation is serious and dynamic. It has the potential to develop dangerously very swiftly and the next few days will be critical.”

He said Ukraine “is sending one of our most experienced brigades to reinforce our troops. The Russians are taking very big casualties and I think this brigade, which I know well, will be able to stop the Russian attack from spreading and then push them back or destroy them.”

Joe Biden has banned imports of Russian-enriched uranium as he looks to disrupt more of Russia’s sources of income amid the war in Ukraine.

The ban on imports of the fuel for nuclear power plants begins in about 90 days, although it allows the Department of Energy to issue waivers in case of supply concerns.

Russia is the world’s top supplier of enriched uranium, and about 24 per cent of the enriched uranium used by US nuclear power plants come from the country.

The law also unlocks about $2.7bn in funding in previous legislation to build out the US uranium fuel industry.

“Today, President Biden signed into law a historic series of actions that will strengthen our nation’s energy and economic security by reducing, and ultimately eliminating, our reliance on Russia for civilian nuclear power,” Jake Sullivan, the national security adviser, said in a statement.

Mr Sullivan said the law “delivers on multilateral goals we have set with our allies and partners,” including a pledge last December with Canada, France, Japan and the United Kingdom to collectively invest $4.2bn to expand enrichment and conversion capacity of uranium.

The waivers, if implemented by the Energy Department, allow all the Russian uranium imports the US normally imports through 2027.

Russian troops have so far entrenched themselves in the villages of Strilecha, Pylna, Borysivka, Krasne, Oliynykove, Mrakovets, Pletenivka, and from there were launching attacks near Hlyboke Zelene Hatysche, and Buchansk.

The capture of the Donetsk city of Avdiivka in February opened a door for the Kremlin’s troops to push westward, deeper into Donetsk. Russia illegally annexed Donetsk and three other regions in 2022 shortly after it invaded Ukraine, and taking control of all of Donetsk is one of the Kremlin’s main war goals.

If Ukraine isn’t able to halt Moscow’s advance, it could create conditions for a possible attack on Kharkiv, Ukraine‘s second-largest city.

It could also create a “buffer zone” to protect Belgorod, where frequent Ukrainian attacks have embarrassed the Kremlin.

In March, Russia announced plans to evacuate about 9,000 children from the Belgorod region because it was being shelled continuously.

Ukraine’s east is witnessing the most intense Russian assault in the current offensive, a US official said, as Russia’s forces also continue to make significant gains near the country’s northern city Kharkiv.

“They (the Russians) are clearly throwing everything they have in the east,” said a US official briefing reporters ahead of US Secretary of State Antony Blinken’s visit to Kyiv.

As of today, Russia controls about 18 per cent of Ukraine’s land and has been gaining ground since October last year, capturing a number of critical towns and settlements.

Last week, Moscow’s troops entered Ukraine near its second largest city of Kharkiv, opening a new, northeastern front in a war that has for almost two years been largely fought in the east and south. The advance could draw some of Kyiv’s depleted forces away from the east, where Russia has been advancing.

US Secretary of State Antony Blinken reached Kyiv today, marking the first high-level visit from the US since Congress passed a long-delayed $61bn military aid package for the country last month.

Blinken arrived in Kyiv by train in the early hours today and hopes to “send a strong signal of reassurance to the Ukrainians who are obviously in a very difficult moment,” said a US official who briefed reporters travelling with Mr Blinken on condition of anonymity.

“The Secretary’s mission here is really to talk about how our supplemental assistance is going to be executed in a fashion to help shore up their defences (and) enable them to increasingly take back the initiative on the battlefield,” the official said.

Artillery, long-range missiles known as ATACMS and air defence interceptors approved by president Joe Biden on 24 April were already reaching the Ukrainian forces, the official said.

He added that Mr Blinken will reassure Ukrainian officials including president Volodymyr Zelensky of enduring US support and deliver a speech focused on Ukraine’s future, the official said.

The Kharkiv incursion has effectively pinned Ukrainian forces in the region, while potentially drawing precious reserves away from heavy battles in the Avdiivka and Chasiv Yar areas of the Donetsk region, where Russia’s advance has been far more significant and strategically important.

Ukrainian local officials said they feared Vovchansk’s fate may mirror that of Bakhmut and Avdiivka, Ukrainian cities where fierce fighting and scorched earth tactics forced Ukrainian withdrawals.

Russian forces were inching closer to Vovchansk, and heavy battles were ongoing on the town’s outskirts.

Using assault infantry units Russian forces are attempting to secure positions in three directions, as Ukrainian forces attempt to dislodge them using firepower. Ukrainian commanders describe the battles as dynamic and complicated.