Mr Clinton "repeatedly" raised the Pope case with the Russian president

After the 20-year sentence was delivered, White House National Security spokesman PJ Crowley said the US was "deeply disappointed" and once again underlined concerns about his health.

Mr Pope has a rare form of bone cancer, and has been denied regular access to a Western doctor since his arrest on 3 April. Nor, according to his lawyer, Pavel Astakhov, has he received "adequate" alternative medical care.

It was not only the US embassy doctor who was denied regular access to his patient. Consular officials were also only allowed to see him occasionally - sometimes at intervals of more than a month.

Russian doctors judged him fit to be tried, although hearings were frequently cancelled because he was too sick to attend.

Retraction

Mr Pope, who does not understand Russian, often complained about his difficulty understanding the proceedings.

Mr Pope is not a spy, was not a spy, and there is no evidence in this case offered to prove he is a spy

Defence lawyer, Pavel Astakhov

He did not trust his translator - an employee of the Federal Security Service - but was refused permission to replace him.

Permission to video-tape the case, so that the translation could be checked later, was also denied.

Mr Pope's defence was that the documents on a new Russian torpedo system that he collected and paid for were all in the public domain.

The truth of this claim is hard for outsiders to judge, as the trial took place behind closed doors.

However, the Russian Security Service's key witness, a professor at Moscow's State Technical University, Anatoly Babkin, retracted during the trial statements he had made earlier to the prosecution.

Spies on the rise

Vladimir Putin: Spy turned president

He denied ever giving Mr Pope secret documents, and said that his initial statements implicating Mr Pope had been extracted under pressure.

Mr Pope is the first Westerner to be tried for spying in Russia for many years. In the past, suspected spies have been expelled, sometimes discreetly, sometimes publicly.

Many analysts interpret the decision to try Mr Pope as a political decision, and a sign of the rising clout of the secret services in Russia, following the elevation of one of their own, Vladimir Putin, to the presidency.