The lawyer for US vice-president Dick Cheney claimed today that the Congress lacks any authority to examine his behaviour on the job.

The exception claimed by Cheney's counsel came in response to requests from congressional Democrats that David Addington, the vice-president's chief of staff, testify about his involvement in the approval of interrogation tactics used at Guantanamo Bay.

Ruling out voluntary cooperation by Addington, Cheney lawyer Kathryn Wheelbarger said Cheney's conduct is "not within the [congressional] committee's power of inquiry".