Russia is interrogating 10 of its sleeper agents deported from the US at a secret facility, it was reported today.

Intelligence officers are using lie detector tests to be sure a double agent did not betray the team to the FBI, reports in Moscow say.

The agents flew to Moscow on Friday in a tense "spy swap" with four people accused of spying for the west. However, nothing has been heard of them since they were whisked away from the capital's Domodedovo airport in a convoy.

The group included the 28-year-old businesswoman Anna Chapman, a former Barclays bank employee who spent several years working in London.

Quoting a source in the security services, the Moskovsky Komsomolets newspaper reported that the agents were first taken to the headquarters of the foreign intelligence service (SVR) in Yasenevo, on the outskirts of Moscow, but were later moved to an unspecified location.

"Specialists are working with the agents," an unnamed source was quoted as saying. "They are trying to find out which intelligence officers [who handled the agents] might have made a blunder.

"They are talking to them and carrying out various tests, including with lie detectors."

The source added that an "enormous amount of work" was being done to establish whether there was a traitor in the SVR who had betrayed the agents. High-ranking SVR officers are thought to have been aware of the agent network since it became active in 2001.

Reports in the US said a 12th person had been detained in connection with the Russian spy ring.

The Wall Street Journal said FBI counter-intelligence agents had been investigating a 23-year-old Russian man for nearly a year, adding that he would be deported.

Meanwhile, realtives of Igor Sutyagin, a Russian scientist convicted of working for the CIA who was sent to Britain as part of the swap, said he had called home a second time.

Dmitry Sutyagin said his brother was still staying in a hotel in a small town near London, but did not know exactly where he was.

The scientist told his mother he had been examined by a psychologist and a doctor. "The doctor said that for someone who has been in prison for 11 years his health is not bad at all," his brother said.

Sutyagin told his family he expected to receive a British visa within the next two days, but had not decided whether he would stay in the country. "Until he's made a sober assessment of the situation, both in Russia and in England, he's not going to make a decision," his brother said.

After earlier suggesting that his movements were restricted, Sutyagin told his mother he was able to walk in woods near his hotel, and he felt as though he was staying at a health resort. He said he was being fed "well and generously" although the food was "unfamiliar".

The 10 spies deported from the US are staying in hotels at a closed SVR facility where there is no mobile telephone coverage.

Relatives can visit them but they will not be allowed to leave the territory for two weeks or more while the "work on mistakes" is conducted, the source added.

If it transpires that the "illegals" – as FBI officers called the agents – committed no errors, they will be released.

The capture of the agents, who used a mix of high and low technology including invisible ink and odd code phrases in ungrammatical English to communicate with their handlers, has caused discomfit in some Moscow circles.

Gennady Gudkov, a former KGB colonel and the deputy head of the parliamentary security committee, said: "Now we know that not only our court system and law enforcement agencies are bad, the last bulwark of the image of our legendary special services has also crumbled."

Opinion is divided over the future of the 10 agents. Some commentators have predicted Chapman – who has been described as "agent 90-60-90"– could become a chatshow host or model.

But Andrei Soldatov, an espionage expert and the editor of agentura.ru, said it was likely the agents would stay under wraps.

"They will probably go to be instructors at the SVR academy, which is a kind of cemetery of agents expelled from other countries," he added.