MOSCOW (AP) — Russia’s deputy foreign minister is brushing back suggestions that an American being held in Moscow on suspicion of spying could be exchanged for a Russian.

Paul Whelan, who also holds Canadian, British and Irish citizenship, was detained in late December. His arrest has led to speculation that Russia could be using him as a pawn to exchange for Maria Butina, the Russian who pleaded guilty last month to acting as a foreign agent in the U.S.

But deputy foreign minister Sergei Ryabkov said Saturday that discussing the issue would be premature because Whelan hasn’t been formally charged, according to Russian news agencies.

“As to the possibility of exchanges of one sort of another, it’s impossible and incorrect to consider the question now, when an official charge hasn’t even been presented,” he was quoted as saying by the state news agency RIA-Novosti.

“Charges will be presented in the near future,” he said, according to the Interfax agency.

Some Russian news reports earlier had cited unnamed sources as saying Whelan had been indicted on charges that could bring 20 years in prison if convicted.

Officials haven’t given details of Whelan’s suspected activities and he was initially identified only as an American. His other citizenships became known on Friday.

U.S. Ambassador Jon Huntsman Jr. visited Whelan on Wednesday in Moscow’s Lefortovo Prison, a 130-year-old facility noted for its strict conditions. Britain, Canada and Ireland have applied for consular access to him.

The 48-year-old Whelan, a former U.S. Marine who left the military with a bad-conduct discharge, is global security director for a U.S. automobile parts manufacturer.

His family back home says his presence in Moscow was nothing more than a visit to attend a wedding. In a Washington Post op-ed published Friday, his twin brother, David, urged the U.S. government to pressure Russia to release him.

“Paul is a kind and considerate brother, son and uncle, and a generous and loyal friend,” he wrote. “He travels as often as he can, both for work and pleasure. He is many things to many people, but he is not a spy.”

Paul Whelan established an account on VKontakte, a social media service similar to Facebook that is popular among Russians, which showed he had scores of contacts in Russia. Many attended universities affiliated with the military, civil aviation or technical studies. Many share his interest in sports and firearms.