The Environmental Protection Agency is telling its pollution enforcement officials not to talk with congressional investigators, reporters and even the agency's own inspector general, according to an internal e-mail provided to The Associated Press.

The June 16 message instructs 11 managers in the EPA's Office of Enforcement and Compliance Assurance, the branch of the agency charged with making sure environmental laws are followed, to remind their staff members to keep quiet.

"If you are contacted directly by the IG's office or GAO requesting information of any kind ... please do not respond to questions or make any statements," reads the e-mail sent by Robbi Farrell, the division's chief of staff. Instead, staff members should forward inquiries to a designated EPA representative, the memo says.

Public Employees for Environmental Responsibility obtained the e-mail and provided it to the AP. The group is a nonprofit alliance of local, state and federal professionals. Its Web site carries the slogan, "Protecting Employees Who Protect Our Environment."

Jeff Ruch, its executive director, said Monday the e-mail reinforces a "bunker mentality" within EPA under the Bush administration.

"The clear intention behind this move is to chill the cubicles by suppressing any uncontrolled information," said Ruch.

The EPA, in an official statement, said Monday the e-mail was aimed at making agency responses to the press, EPA's inspector general and Congress' General Accountability Office more efficient, consistent and coordinated. The EPA also said officials could still talk to investigators as long as they checked in with the appropriate representatives. About 900 lawyers and technical support staff are employed by the division at EPA headquarters in Washington.

"There is nothing ... that restricts conversation between enforcement staff, the press, GAO and the IG, and the procedure is consistent with existing agency policies," the statement said. "No one has to get permission or approval to speak with the IG or GAO."

The e-mail, according to EPA, was a response to a May 2007 audit by the Inspector General's Office that found the agency had not responded to earlier IG reports on problems with water enforcement and other matters. However, the audit did not make any specific recommendations about communications between staff and the inspector general's office.

In a statement issued Monday, the Office of Inspector General said it did not approve of the language in the e-mail and was engaged in discussions with enforcement officials to ensure the electronic dispatch would not hinder its access to information.

"All EPA officials and employees are required to cooperate with OIG," the statement said. "This cooperation includes providing the OIG full and unrestricted access to EPA documents, records, and personnel."

A spokesman for the congressional GAO said Monday that that agency will deal with access issues as they arise.

The EPA is currently under pressure from several congressional committees to disclose documents relating to its position on global warming and its denial of a petition by California to control greenhouse gases from motor vehicles. Just last week, EPA Administrator Stephen Johnson denied a request to appear before two Senate committees to discuss whether the agency's decisions comply with its staff's technical and legal recommendations.

Sen. Barbara Boxer, the California Democrat who heads the Senate environment committee, said Monday the administrator had turned "the EPA into a secretive, dangerous ally of polluters, instead of a leader in the effort to protect the health and safety of the American people."

In a letter sent to EPA's inspector general on Friday, Senate Judiciary Chairman Patrick Leahy, D-Vt., asked for a probe into President Bush's claims of executive privilege over the California documents and other "White House interference" into decisions by the agency.

On Monday, Leahy said, "I hope this e-mail is not akin to the wide range of tactics this administration has used to thwart accountability."