Pavel Popovich, a leading figure in the pioneering generation of early cosmonauts and the fourth Soviet man to go to space, died on Wednesday at a sanatorium aged 79, space officials said.

Popovich is best known for piloting the Vostok-4 probe that in August 1962 took part in the first ever instance of two manned satellites orbiting the earth at the same time, a trip that made him the sixth human in orbit.

The other probe, Vostok-3, was piloted by Andriyan Nikolayev, who died in 2004. Popovich also took part in a longer 15-day mission as commander of the Soyuz-14 spacecraft in July 1974.

"Pavel Romanovich Popovich died Wednesday in one of the sanatoriums in Crimea. Now everything is being done to take his body to Moscow," the head of the federation of cosmonauts, Vladimir Kovalenok, told ITAR-TASS news agency.

"He was one of the few people who not only had no enemies, but only had friends. With this guy you could go into flames, into water, on an intelligence mission, whereever," he added.

ITAR-TASS quoted sources as saying that Popovich died of a stroke. He was five days short of his 80th birthday.

Popovich, born in 1929 in the Kiev region of what is now Ukraine, was part of a pioneering team of cosmonauts who were trained to pilot the Vostok craft that were the first manned probes the Soviets sent into space.

In a 2002 interview, Popovich recalled a mid-orbit conversation with Nikolayev during their landmark double flight, when he operated under the call name Golden Eagle.

"Andriyan said 'Golden Eagle, Golden Eagle, this is Falcon! Do you hear me?' And I said 'Hello Andriyan! I can not only hear you but I can see you! You are flying by on my right, like a little moon.'"

The cosmonaut, whom contemporaries rememberd as a witty man who loved company, always described himself as the first Ukrainian to go to space.

He was the eighth man in space but the sixth man to go into orbit after the first two manned US spaceflights did not go into earth orbit.

Popovich later took part in the Soviet manned lunar programme which was shut down after failing to beat the United States to put a man on the moon. Popovich won two Hero of the Soviet Union awards, his country's highest honour.

The first Soviet man in space, Yuri Gagarin, died in a plane crash in 1968 while the second, Gherman Titov, died in 2000.

Popovich's death came the same day as the blast-off of a Russian cosomonaut, a US astronaut and a Canadian space tourist on a Soyuz rocket on the latest mission for the International Space Station.