US prosecutors unsealed an indictment Monday charging the co-director of a think tank with illicit arms trafficking, violating US sanctions laws, and other charges, five months after he was arrested in Cyprus and fled from authorities.

The US-Israeli citizen, Gal Luft, co-director of the Institute for the Analysis of Global Security, is also someone is also someone House Oversight Chairman James Comer, a top Republican, has described as an informant claiming to have incriminating information on Hunter Biden.

Luft has tweeted denials of the allegations, saying in February, "I've been arrested in Cyprus on a politically motivated extradition request by the US. The US, claiming I'm an arms dealer. It would be funny if it weren't tragic. I've never been an arms dealer. DOJ is trying to bury me to protect Joe, Jim&Hunter Biden."

An attorney for Luft did not immediately respond to a request for comment. CNN has reached out to the Institute for the Analysis of Global Security.

Luft is a fugitive, prosecutors say.

Luft was charged with failing to register as an agent for China in the US, including in 2016 acting through a former high-ranking US official who was then advising President-elect Donald Trump. He was also charged with acting as a middleman to aid Chinese companies buying weapons. The indictment also alleges Luft violated US sanctions by attempting to broker sales of Iranian oil.

House Republicans are investigating the Biden family's financial dealings and have requested information from the Justice Department about its investigation into Hunter Biden, who has agreed to plead guilty to two tax misdemeanors. At least one Republican, Sen. Ron Johnson of Wisconsin, has claimed that Luft is an important witness in that investigation.