Gagarin was the first human to view Earth from space

It was signed by the space pioneer on 15 April, 1961, three days after his flight.

In the document Gagarin, who was 27 at the time, described what he saw as the first man to look at Earth from space.

"The Earth from an altitude of 175-327 kilometres can be seen quite well ... Large mountain ranges, big rivers, large forest tracts, shorelines, and islands. ...

"One can see the shadow of ...clouds on the Earth," wrote Gagarin, who died in 1968 while test-flying a MiG-15 fighter plane.

The manuscript was bought by an unidentified American telephone bidder during a sale of space memorabilia at Christie's auction house in New York.

Origin questioned

However, Gagarin's widow, Valentina, told a Moscow radio station on Wednesday that the auctioned document could at best only be a copy because the original, kept in a Moscow archive, would never be released for sale.

"Only authorised persons had access to such archive documents, of which only three copies were made"

Yuri's widow Valentina Gagarin

"These documents were never shown and have never been released to the family," she said. "Only authorised persons had access to such archive documents, of which only three copies were made."

She admitted that illegal copies might have been made, but stressed she knew nothing of their existence. She said she had never personally seen any documents concerning her husband's mission aboard the Vostok.

The Russian newspaper Sevodnya says that the seller of the document in New York might be Cuban leader Fidel Castro.

It quoted a Russian culture ministry official as saying the late Soviet leader Nikita Khrushchev had given Castro a copy in 1963. But Russia's chief archivist Vladimir Kozlov said there was no evidence of any such presentation.