The White House has systematically manipulated climate science for years to play down the dangers of global warming, a US congressional report says.

Monday's report, prepared by Democrats after a 16-month investigation, came as the Bush administration pressed a UN climate meeting to drop targets for big cuts in greenhouse gases by rich nations.

"The Bush administration has engaged in a systematic effort to manipulate climate change science and mislead policymakers and the public about the dangers of global warming," the report said.

Suppression

The report said that the White House Council on Environmental Quality (CEQ) exerted "unusual control" over what federal scientists could say publicly about climate change, and that it was standard practice for the council to decide whether or not US scientists could give interviews to the media.

It said the White House had over the years suppressed scientific views that conflicted with administration policy and extensively edited government reports "to minimise the significance of climate change".

The report looked at hundreds of internal communications and documents as well as testimony at two congressional hearings to outline a pattern where scientists and government reports were edited, to emphasis the uncertainties surrounding global warming, Henry Waxman, a Democrat who issued the report on Monday, said.

Many of the allegations of interference dating back to 2002 have surfaced previously, although the report by the Democratic majority of the House Oversight and Reform Committee sought to show a pattern of conduct.

Some republicans called it a "partisan diatribe" against the Bush administration.

James Connaugton, the CEQ chairman, said "claims that this administration interfered with scientists and with the science are false".

Tom Davis, the ranking Republican on the committee, issued his own report disputing the Democrats' conclusions.

He said the Democrats "grossly exaggerated" claims of political interference and ignored "the legitimate role of policymakers, instead of scientists, in making administration policy".

The White House called the findings "rehash and recycled rhetoric" that has been addressed by administration officials in the past.

"It's a thinly veiled attempt to distract attention from the administration's efforts ... at the Bali summit," Emily Lawrimore, a White House spokeswoman, said.

Bali block

The report was issued as government officials from across the globe were meeting in Bali, Indonesia, to map out a strategy for dealing with climate change after 2012 when the Kyoto Protocol on climate change expires.

On Monday, the US urged participants in Bali to drop a 2020 target for deep cuts in greenhouse gases by rich nations, from guidelines for a new pact to widen the UN's Kyoto Protocol to slow global warming beyond 2012.

Harlan Watson, the chief US climate negotiator, said the tough targets included in a draft document in Bali would be "prejudging what the outcome should be".

"We don't want to start out with numbers," Watson said.

A delegate familiar with the draft negotiations said there had been "a lot of pressure" from the US to remove the targets but "the numbers are still in the text".

The Kyoto Protocol, which was signed 10 years ago on Tuesday, binds 36 industrial nations to cut emissions, mainly from burning fossil fuels, by 5 per cent below 1990 by 2012.

The draft text for the new pact suggests that rich countries such as the US should aim to cut emissions of climate-warming gases by between 25 and 40 per cent below 1990 levels by 2020.

Watson's push for the targets to be removed is consistent with the Bush administration's long-term stance on climate change.

While acknowledging the reality of global warming, the White House has opposed specific targets to reduce the emissions of greenhouse gases such as carbon dioxide - spewed by coal-fired power plants and petroleum-fuelled vehicles - arguing that this would hurt the US economy.

Washington has also stressed that any successor agreement to Kyoto must include all countries with high greenhouse emissions, including fast-growing China and India, which are not legally bound by the pact's targets.

The US is the only industrialised country not to have ratified the Kyoto Protocol while China has said it will not back binding emissions curbs that could affect its booming economy.

Stop blame game

Al Gore, the former US vice-president turned climate campaigner, urged the US and China to join the fight against global warming as he accepted the Nobel Peace Prize on Monday.

"Both countries should stop using the other's behaviour as an excuse for stalemate and instead develop an agenda for mutual survival in a shared global environment," said Gore, who was jointly awarded the prize with the UN's top climate panel.

"It should be absolutely clear that it is the two largest CO2 [carbon dioxide] emitters, and most of all my own country, that will need to make the boldest moves," he said.

"It's unfortunate that my country, which I believe should be the leader of the world, is now blocking action in Bali."

Robert Cluck, the Republican mayor of Arlington, Texas, George Bush's home state, said the US president's failure to sign the Kyoto Protocol did not mean American cities could not take the lead on cutting emissions in their own backyards.

Across the US, more than 700 mayors, representing 75 million Americans, have pledged to meet the standards proscribed by the Kyoto Protocol.

Although his call for cutting emissions has not played well with "big oil" Republicans in Texas, Cluck, also a doctor, maintains that the state's greenhouse gas emissions - the deadliest levels of carbon dioxide pollution in the US - are shameful, inexcusable and embarrassing.

PHOTO CAPTION

Then-Vice President Al Gore, center, shakes hands with Japanese Prime Minister Ryutaro Hashimoto, right, as Japanese Foreign Minister Keizo Ouchi looks on prior to their talks in Kyoto, western Japan, in this December 8, 1997, file photo. (AP)