Gary Powers & Fred Pryor

American spy plane pilot Captain Francis "Gary" Powers has been freed from prison in the Soviet Union in exchange for a Russian spy jailed in the US.

Gary Powers was sentenced to 10 years in a Soviet prison after his U-2 plane was shot down over Russia in May 1960.

But on Saturday Captain Powers, 32, walked into West Berlin across a bridge separating the city's east and western sectors.

At the same time Russian spy Colonel Rudolph Abel crossed in the opposite direction.

Colonel Abel had served five years of a 30-year term for running a spy ring in the US.

His sentence was commuted by US Attorney-General Robert Kennedy two weeks ago.

However, the Russians have always denied any knowledge of Colonel Abel and even now maintain Mr Khrushchev freed the US pilot simply as a "goodwill gesture".

Another American, student Frederic Pryor, was also freed from the eastern bloc at the same time as Gary Powers.

Mr Pryor had been held in East Germany without charge since last August.

'Weather plane'

Gary Powers' capture in 1960 caused an international crisis.

Initially the American authorities believed there was no evidence left of either plane or pilot and tried to convince the Russians the U-2 had been a weather plane.

However, the Russians then produced Mr Powers alive and well claiming he had admitted spying for the CIA.

Russian leader Nikita Khrushchev demanded an apology from US President Eisenhower and when none was forthcoming plans for a superpower summit in Paris collapsed.

US authorities have said it will be at least a week before the freed airman is allowed to meet the press.

In the meantime they will no doubt want to establish how Mr Powers came to be shot down when U-2s were believed to be impregnable to anti-aircraft fire.

They will also be keen to find out exactly how much Mr Powers told his captors about the spy planes.

There was speculation during his trial that he had said more than his oath of secrecy permitted.

The release of Captain Powers comes a year after that of the two US airmen whose reconnaissance aircraft was shot down over the Barents Sea in January 1960.

Four of the crew died. Authorities in the USSR claimed the plane had been in Soviet airspace.

The two survivors, John McKone and Freeman Olmstead, were held in prison in Moscow for a year before being freed.