“Complete silence” is required regarding a possible prisoner exchange involving the Western journalist Evan Gershkovich, the Kremlin has said.

“As for exchange matters, we have repeatedly stressed that there are certain contacts, but they must be carried out in absolute silence,” Dmitry Peskov, a Kremlin spokesman, said.

The Wall Street Journal reporter was arrested in Russia almost a year ago on suspicion of espionage and this week had his pre-trial detention extended until 30 June.

In response to the Moscow hearing,  Lynne Tracy, the US Ambassador to Russia, said the Kremlin was using Mr Gershkovich and other American citizens as pawns.

The Kremlin’s calls for silence on the matter echo Vladimir Putin’s comments in his February interview with Tucker Carlson. “The more public we render these things of this nature, the more difficult it becomes to resolve them. Everything has to be done in a calm manner,” the Russian leader said.