Environmental advocates have accused the Bush Administration of delaying the release of the 149-page report so that it could avoid regulating greenhouse gases.

They claimed that the Bush Administration has worked to discourage a link between public health and climate change, fearing this would compel the government to regulate greenhouse gases

According to The Telegraph , the report was prepared as part of a response to a 2007 Supreme Court ruling under the Clean Air Act, which found the Environmental Protection Agency must regulate greenhouse gases unless there was a scientific reason not to.

The paper says that the report lays out for the first time the scientific case for the grave risks that global warming poses to people, and to the food, energy and water on which society depends.

"Risk (to human health, society and the environment) increases with increases in both the rate and magnitude of climate change," said the scientists at the Environmental Protection Agency.

Global warming, they wrote, is "unequivocal," and humans are to blame.

"This document inescapably, unmistakably shows that global warming pollution not only threatens human health and welfare, but it is adversely impacting human health and welfare today," said Vickie Patton, deputy general counsel for the Environmental Defence Fund.

"What this document demonstrates is that the imperative for action is now," Patton added.

On Friday, the White House dismissed the scientists' findings, when it said the Clean Air Act was the wrong tool to control global warming pollution and said that a new law, which dealt solely with global warming, was needed.

Stephen Johnson, the EPA chief, said through a spokesman that although he knew "the science is clear, and that climate change is a significant issue," he did not want to make a "rash decision under the wrong law".