This is a very serious matter that involves the right of the Congress to oversee the executive branch and the need for transparency and accountability

GAO comptroller general

BBC correspondent Jonny Dymond says this could be the first time the GAO resorts to the courts in its 80-year history.

News of possible court action followed the White House's rejection of a letter from the GAO on Thursday demanding that business leaders who met Vice President Dick Cheney and aides to discuss the policy be identified.

White House officials said that the GAO is exceeding its powers, adding that the administration was confident that the GAO did not have the legal authority to request the information.

The inquiry is being conducted at the behest of Democrats in Congress, who believe Mr Cheney consulted extensively with friends and acquaintances in the corporate energy sector and spent little, if any, time hearing the views of environmental advocates.

Need for transparency

Requests and refusals have been going back and forth across Washington between the GAO and Mr Cheney since May.

Mr Walker said that the dispute had serious potential implications for the Congress and the American people.

Democrats are the driving force behind the inquiry

"This is a very serious matter... [that] involves several fundamental good government principles, including the right of the Congress to oversee the executive branch and the need for transparency and accountability," he said.

At the heart of the dispute is the Democrats' conviction that the energy plan was the product of closed-door dealings between Mr Cheney, who until recently ran an energy corporation, and his erstwhile industry friends.

Environmentalists believe that the White House has shut them out of the information-gathering process.

The plan calls for an expansion of oil, natural gas and coal production, as well as some environmental initiatives.

White House officials have dismissed the Democrats' claims as partisan nonsense.

They say their energy plan is the only way to safeguard America's 21st Century energy supply.