Russian news agencies said 59-year-old Poteyev was convicted of treason and desertion but gave no details about a possible sentence.

Prosecutors had demanded a 25-year jail sentence but Poteyev is unlikely to spend any time in jail because Russian officials believe he is currently hiding in the United States.

“Poteyev’s actions delivered a considerable blow to Russia’s national security,” the Interfax news agency quoted the presiding judge as telling the closed-door hearing.

Security analysts said the cell’s detection last summer inflicted severe damage to Russia’s foreign intelligence efforts and revealed weaknesses in a surveillance programme that had been Moscow’s pride since Soviet times.

The Russians’ main job was to blend in with young US professionals and get hired at top state agencies and private firms that dealt with advanced technologies and other sensitive data.

The group of US East Coast spies included Anna Chapman, the 29-year-old redhead who has turned her glamourous looks and background into a lucrative Russian career as an A-list celebrity and television presenter.

Russian news agencies said Poteyev had until last year served as the deputy head of the US department of Directorate S — a covert operations department involved in placing sleeper agents in foreign countries who try to pass off as locals.

The two-month hearing reportedly included testimony from Poteyev’s wife — who is still based in Moscow — and Russian intelligence officers.

Interfax said the court was told that Poteyev had professional access to a list of Russian sleeper agents in the United States and had at one stage sold it to the US Central Intelligence Agency.

The United States in return reportedly provided Poteyev with false documents that secured his escape from Moscow by train to the Belarussian capital Minsk.

Interfax said the presiding judge read a telephone text message that Poteyev reportedly sent his wife as he was fleeing that warned he would “never be back”.

“Mary, try to take this calmly. I am not leaving for a bit, but forever. I did not want to, but I had to. I will start a new life and try to help the children,” the Russian colonel reportedly texted his wife.

Last summer’s exposure of the spies left some intelligence officials conceding that their US surveillance programme had been set back by up to a decade.

Former spy and current Prime Minister Vladimir Putin used a national television appearance in December to call the double agent a “pig” who will “regret it a thousand times over”.

Washington announced the Russians’ arrest just days after Russian President Dmitry Medvedev left the United States after holding talks with his US counterpart Barack Obama last June.

Medvedev went out of his way to stress after the expulsion that the case would not harm the two former Cold War enemies’ ties.

The 10 spies were personally greeted on their return by Putin who even sang patriotic songs with them in front of television cameras.

Several besides Chapman have also managed to establish lucrative business careers.