WASHINGTON (Reuters) - Nearly 900 scientists at the Environmental Protection Agency have experienced political interference in their work in the last five years, the Union of Concerned Scientists reported on Wednesday.

The White House is pictured in Washington, early January 28, 2008. REUTERS/Jonathan Ernst

The nonprofit environmental organization said its investigation of EPA was in line with previous probes of other U.S. agencies which found “significant administration manipulation of federal science.”

A government spokesman denied this, and said scientific findings were balanced with policy concerns.

“Our investigation found an agency in crisis,” said Francesca Grifo of the Union of Concerned Scientists, referring to the Environmental Protection Agency. “Distorting science to accommodate a narrow political agenda threatens our environment, our health and our democracy itself.”

The report included interviews with current and former staff members, analysis of government documents and a questionnaire sent to 5,419 EPA scientists, which generated 1,586 responses.

Of those responses, 889 scientists or 60 percent, said they had personally experienced at least one instance of political interference in the last five years; 394 said they experienced frequent or occasional “statements by EPA officials that misrepresent scientists’ findings.”

More than one-fifth, or 285, said they had experienced “selective or incomplete use of data to justify a specific regulatory outcome,” the report said.

Nearly 100 scientists said the White House Office of Management and Budget (OMB) was the main offender.

“OMB and the White House have, in some cases, compromised the integrity of EPA rules and policies; their influence, largely hidden from the public and driven by industry lobbying, has decreased the stringency of proposed regulations for nonscientific, political reasons,” one scientist wrote in response to the investigation.

A spokesman for EPA, Jonathan Shradar, denied these allegations.

“Certainly OMB plays a policy role,” Shradar said by telephone. “It’s important that there is inter-agency cooperation. There’s not interference against the scientific work that they’re doing, that’s still highly respected and taken into account.”

U.S. Rep. Henry Waxman, a California Democrat who chairs the House of Representatives Committee on Oversight and Government Reform, called on EPA Administrator Stephen Johnson to respond to questions about the report at a committee hearing in May.

The EPA has come under fire recently for its standard for ground-level ozone, which critics claim is too high. The agency is also in a court fight with 18 U.S. states over its failure to limit greenhouse gas emissions from new cars and trucks, more than a year after the Supreme Court ruled EPA had the power to do so.