David Walker, comptroller general for congressional watchdog, the General Accounting Office will answer questions about the GAO's attempts to get George Bush's second in command to reveal details of Enron executives involved in the creation of energy policy last year.

In particular the GAO wants Cheney to release information about the special energy taskforce he headed.

According reports on BBC online, former Enron chief executive Kenneth Lay gave generous donations to president Bush's election campaign. Lay refused to testify before a congressional hearing, invoking his Fifth Amendment rights.

The Bush administration argues that Congress has no right to study such documents as the vice president's office goes beyond the GAO's mandate to oversee government agencies.