If found guilty by the Russian court, Whelan could face up to 20 years in prison.
Paul Whelan is pictured in this undated photo released by his family. He was arrested by the Russian special security services (FSB) and accused of being an American spy who had tried to recruit Russian nationals via social media.
A former US Marine who now works as head of security for a MI auto parts company, Mr Whelan holds US, British, Canadian and Irish passports as a result of his family's emigration. "We urge the U.S. Congress and the State Department to help on Paul's behalf to secure his release and return him home soon", the family said.
Britain's foreign secretary, Jeremy Hunt, last week warned Russian Federation against using "individuals as pawns in diplomatic leverage". "We need to see what those charges are against him to understand whether there is a case or not".More news: Bumrah rested for Australia ODIs, New Zealand tour
Whelan's twin brother David wrote in an op-ed in Friday's Washington Post that his brother is not a spy.
On January 9, the Kremlin denied Western allegations that it was using Whelan as a pawn in a political game.
Russian Federation "carries out counterintelligence activities against those who are suspected of espionage", Peskov said.
Whelan has lived and worked most of his life in the U.S. He holds Canadian, American, British and Irish citizenship.More news: Blue Jays trade Martin to Dodgers
Whelan's Russian lawyer has suggested that Whelan could later be exchanged for Russians held in USA jails, including Butina.
Whelan's lawyer, Vladimir Zherebenkov, said on January 3 that he filed a complaint with the Lefortovo court because the detention without bail is "excessive and unwarranted".
Russia has raised its own suggestions that the USA has taken its own hostage after the Federal Bureau of Investigation arrested a Russian man on arms smuggling charges.More news: Rep. Ocasio-Cortez's campaign paid $1,500 fine to NY state