In an interview published last week, the 53-year-old Whelan told the BBC that he feels "abandoned" and betrayed by his country after being imprisoned in Russia on espionage charges.

Whelan was detained on December 28, 2018 and is serving a 16-year sentence for spying, a charge the US government says is without merit.

"For far too long, Paul and his family have suffered the consequences of the Russian government's decision to wrongfully detain US citizens," Blinken said in the statement.

"Not a day goes by without intensive US government efforts to bring Paul home," Blinken said. "We will not rest until he is safely back with his family where he belongs."

Whelan is currently in a prison in Mordovia -- some 250 miles (400 kilometers) southeast of Moscow -- a region notorious for its harsh jails.

He worked in security for a US vehicle parts company when he was arrested in Moscow and has always asserted that the evidence against him was falsified.

In November Whelan was assaulted by a new inmate who hit him in the face and broke his glasses, according to his brother David Whelan, who said other inmates eventually came to his aid.

Russia and the United States each accuse the other of detaining each other's nationals for political purposes.

"Using people as political pawns is unacceptable," Blinken said in the statement.

In March Russia arrested another US citizen, Wall Street Journal reporter Evan Gershkovich.

The White House said last week it was preparing a new proposal to Russia to seek the release of the two imprisoned Americans after Moscow rejected an earlier attempt.

Last December Russia released basketball superstar Brittney Griner, who had been held since February 2022 on charges of possessing vape cartridges with a small quantity of cannabis oil.

But her release came only in exchange for notorious Russian arms dealer Viktor Bout -- known as the "Merchant of Death" -- who had been jailed in the United States.