Accusations that a giant of astronomy, Edwin Hubble, quashed a Belgian cleric who beat him to making one of the greatest discoveries of modern times are unfounded, Nature said on Wednesday.

Hubble's reputation has been recently tarnished by suggestions that he, or an ally, ensured that Georges Lemaitre, a little-known Catholic priest and mathematician in Brussels, failed to get credit for discovering that the Universe is expanding.

This discovery is key to the theory that the Universe was born in the "Big Bang" some 14 billion years ago.

And it underpins the stark hypothesis -- rewarded with the Nobel Prize for Physics this year -- that endless expansion will eventually rip all matter apart, leaving the cosmos a frigid place of disconnected atoms.

It was in 1927 that Lemaitre published, in French, his paper in an obscure Belgian journal, the Annals of the Scientific Society of Brussels.

Two years later, Hubble in the United States published his own paper.

He put forward calculations that later became enshrined as "Hubble's law" and "Hubble's constant," relating to the speed at which a galaxy appears to recede from our view.

In 1931, the English translation of Lemaitre's 1927 paper was published in the world's top astronomical journal of the time, the Monthly Notices of the Royal Astronomical Society.

But, oddly, it did not include key paragraphs from the original text in which Lemaitre had described the same things as Hubble.

As a result, dark suggestions have been voiced in books and astronomical publications this year that this was a case of censorship.

The deletions, according to these conspiracy theories, were intended to undermine any claim by Lemaitre to have been the first with the great insight.

Intrigued by the mystery, Mario Livio of the Space Telescope Science Institute in Baltimore, Maryland, delved deep into archives in London and Brussels.

Reporting in Nature, Livio found that the editor of the astronomical journal had sought out Lemaitre, inviting him to set down his findings for the record.

Lemaitre, at the journal's request, did the translation of his original text.

But the correspondence also shows Lemaitre deliberately left out several paragraphs and footnotes, saying he believed this data had been superseded by new research, said Livio.

"This clearly ends speculation about who translated the paper and who deleted the paragraphs -- Georges Lemaitre did both himself," Livio said.

"Lemaitre was not at all obsessed with establishing priority for this original discovery. Given that Hubble's results had been published in 1929, Lemaitre saw no point in repeating his own more tentative earlier findings in 1931."

Hubble -- after whom the US Hubble Space Telescope is named -- died in 1953, leaving behind a reputation for languid brilliance.

His early passion was for sport, including amateur boxing; he trained initially as a lawyer but got bored and switched to astronomy; and he adopted British mannerisms and fashions that irritated many of his peers.