U.S. Senator Frank Lautenberg is asking the Justice Department to investigate oil company executives about apparent discrepancies in testimony to Congress.

In a statement, the Democratic Senator noted providing false testimony to Congress is a violation of federal law.

At a hearing last week, the chief executives of five oil companies denied that their firms participated in secret policy meetings with an energy task force headed by Vice President Cheney in 2001.

The companies are ExxonMobil, Chevron, ConocoPhillips, BP, and Shell.

But the Washington Post reports that a White House document shows that oil company representatives did meet with a key official of the group.

Environmentalists have accused the Cheney task force of shutting them out of energy policy discussions in favor of the oil industry.

Two watchdog groups unsuccessfully sued the White House to obtain records of the meetings, which were held in secret.