A new batch of hacked emails thought to come from a British climate research unit at the centre of controversy in 2009 were posted online Tuesday in a suspected bid to disrupt forthcoming UN talks.

The release of hundreds of emails from the University of East Anglia (UEA)'s climatic research unit two years ago ahead of the unsuccessful UN Copenhagen summit sparked a fierce row.

Climate change sceptics claimed the emails from the unit in eastern England showed that scientists had manipulated and suppressed key data to support a theory of man-made global warming.

Three separate inquiries have since largely cleared scientists at the unit of wrongdoing over their research.

The university said that some 5,000 emails released Tuesday appeared to have come from the unit, and accused the perpetrator of trying to repeat the controversy of two years ago ahead of the talks in Durban opening Monday.

UEA said that, while it was impossible to check immediately that all the emails were genuine, the release seemed timed to "cause maximum disruption to the imminent international climate talks."

It said in a statement there was "no evidence of a recent breach in our systems" and it suspected the emails came from the original batch stolen two years ago.

"This appears to be a carefully timed attempt to reignite controversy over the science behind climate change when that science has been vindicated by three separate independent inquiries and a number of studies," it said.

"As in 2009, extracts from emails have been taken completely out of context."

The emails were released on a Russian server, the BBC and The Guardian newspaper reported.

Phil Jones of the British climate unit and Michael Mann of Penn State University in the United States are among the reported authors of the emails.

The UN climate talks in South Africa will test international resolve to tackle global warming, with analysts warning of a confrontation over the Kyoto Protocol, the only agreement setting legal curbs on greenhouse gases.