NEW YORK — US officials Wednesday laid formal charges against 11 alleged members of a Kremlin spy ring, as Russia and the United States were said to be planning a dramatic Cold War-style prisoner swap.

Justices ordered two suspects detained in Boston and three in the Washington area to be transferred to New York, where they will join five already there.

All 10 were to appear Thursday before a judge in federal court, the US prosecutor's office for Manhattan announced.

The 10 alleged Russian "deep cover" sleeper agents were arrested on June 27 in an FBI swoop that recalled shadowy Cold War hostilities and threatened to upset efforts to reset ties between the superpowers.

An 11th suspect, accused Kremlin paymaster Christopher Metsos, was arrested in Cyprus the following day but freed on bail and subsequently vanished.

They are all accused of "conspiring to act as secret agents in the United States on behalf of the Russian Federation and nine of these individuals with conspiracy to commit money laundering," the formal indictment said.

The charges were the same as those mentioned last week in the FBI's criminal complaint and carry maximum sentences of 20 years for money laundering and five for the conspiracy allegations.

Moves to gather all the alleged spies together in New York came as it was claimed the Russian and US governments were planning a spy swap deal to avoid potentially embarrassing and diplomatically damaging court battles.

Russian lawyer Anna Stavitskaya told a press conference in Moscow that her client Igor Sutyagin, jailed in 2004 on charges of spying for the CIA, had been told he would be released as part of the swap.

"He is going to be exchanged for the people who are being accused of espionage in the United States," Stavitskaya said.

Russian arms expert Sutyagin was convicted in 2004 of handing over classified information to the United States, via a British security company that Russia claimed was a CIA cover, and sentenced to 15 years in jail.

Russian officials and the White House refused to comment on the spy swap claim. "This is a law enforcement matter that is being handled that way," said White House spokesman Robert Gibbs.

Neither Russia nor the United States wants the case to damage relations and both have a stake in avoiding a prolonged trial that could expose sensitive information to a global media glare.

Sutyagin's brother Dmitry Sutyagin said his brother had told the family that the idea of an exchange came from the Americans.

"The Americans presented a list of people for whom they were ready to exchange the people detained in America accused of espionage. Igor was among them."

He added that under the deal his brother, who had already been moved to Moscow from his prison in the Russian far north earlier this week, would be transferred to Vienna, from where he would fly on to London.

A former spokesman for the Russia's Foreign Intelligence Service (SVR), Yury Kobaladze, told Echo of Moscow radio that an exchange would be a "wonderful way out of a very complex situation."

Exchanges of captured agents between Western and Eastern powers were a regular tactic in the Cold War, sometimes on the Glienicke Bridge between East and West Germany.

The Russia spy case erupted just three days after US President Barack Obama held a chummy White House summit with Russian counterpart Dmitry Medvedev, but both sides have played down the notion of any diplomatic fallout.

The suspects are accused of being part of the "Illegals" program, a covert operation set up by the SVR, a successor to the Soviet-era KGB, to infiltrate US policy-making circles.

None were charged with the more serious crime of espionage, apparently because there is no proof they passed significant secretive information to their Kremlin spymasters.

Only Vicky Pelaez, a well-known Peruvian-American journalist who was married to one of the other four New York suspects, has been granted bail, under house arrest.

However, she too remains in custody pending an appeal by prosecutors, who say she is a serious flight risk. A bail hearing for Pelaez was set for Friday.