According to American media reports, US oilfield services company Halliburton changed its accounting methods to boost revenue while the current US Vice-President, Mr Dick Cheney, was chief executive of the company.

In 1998, Halliburton started to count cost over-runs on construction projects as revenue on the assumption that its customers would pay at least part of the cost.

Normal accounting practice dictates that revenue from cost over-runs should be counted only after settling with customers.

Media reports suggested that Halliburton adopted the aggressive accounting methods to obscure losses, citing two former executives of Dresser Industries, which was acquired by Halliburton in 1998.

As chief executive, Mr Cheney had ultimate responsibility for Halliburton's books and according to one auditing expert, the changes stretched and "possibly" broke US accounting rules.

As might be expected, the current US Vice President declined to comment on the matter.