US urges Russia to release detained newspaper reporter

US President Joe Biden has urged Russia to release Wall Street Journal reporter Evan Gershkovich after the country's security service arrested him on espionage charges - allegations that the newspaper denies.

"Let him go," Biden told reporters at the White House on Friday morning when asked about his message to Russian authorities on the arrest of Gershkovich.

Russia's Federal Security Service has accused Gershkovich, a US citizen, of trying to obtain classified information.

It is the first time a US journalist has been detained on accusations of spying since the Cold War.

The WSJ has said it "vehemently denies" the charges.

The US administration said on Thursday that it was working to secure consular access to Gershkovich.

Asked on Friday morning whether he would expel Russian diplomats or journalists in the US, Biden responded: "That's not the plan right now."

White House press secretary Karine Jean-Pierre called the targeting of US citizens in Russia "unacceptable" and that the administration condemns the detention of Gershkovich "in the strongest terms".

The US government has also warned US citizens not to travel to Russia, and for those in the country now to depart immediately.