Russia's Foreign Ministry says the United States detained a Russian citizen the day after a former US marine was arrested in Moscow on spying charges.

Key points: Former US marine Paul Whelan was arrested in Moscow on December 28 on spying charges

Former US marine Paul Whelan was arrested in Moscow on December 28 on spying charges Dmitrii Makarenko was arrested in a US territory on December 29

Dmitrii Makarenko was arrested in a US territory on December 29 The suggestion of a prisoner swap has been played down by Russia's Deputy Foreign Minister

US federal court records show Dmitrii Makarenko was arrested in the American territory of the Northern Mariana Islands on December 29.

He is wanted in Florida on one count of conspiracy to export defence articles without a licence, four counts of attempting to export defence articles without a licence, and two counts of money laundering.

He was arrested the day after Russian authorities detained former US marine Paul Whelan, who has been accused of spying.

Mr Whelan, who also holds Canadian, British and Irish citizenship, was arrested by Russia's Federal Security Service on December 28.

His family say he is innocent and that he was in Moscow to attend a wedding.

The Russian Foreign Ministry said the US detained Mr Makarenko on December 29 and had since moved him to Florida.

"Mr Makarenko, born in 1979, has arrived on Saipan Island with his wife, underage children and elderly parents. He was detained by FBI personnel at the airport right after his arrival," the ministry said.

The Russian ministry said in its statement that Russian diplomats had not been able to reach Mr Makarenko in Florida and said Washington had yet to explain his detention.

Before Moscow gave details of Mr Makarenko's detention, experts had speculated that Moscow could exchange Mr Whelan for other Russians held by Washington.

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Commenting on that possibility, Russian Deputy Foreign Minister Sergei Ryabkov was quoted by Interfax news agency as saying: "I see no reasons to raise this issue in context of exchanges. We should undergo all the procedures needed in this situation."

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

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

The accusations from both sides could further complicate the already strained relationship between Moscow and Washington, despite the professed desire of presidents Donald Trump and Vladimir Putin to build a personal rapport.

US Secretary of State Mike Pompeo said this week that Washington had asked Moscow to explain Mr Whelan's arrest and would demand his immediate return if it determined his detention is inappropriate.

ABC/wires