Link to Enron: O’Neill is reported to have received at least two telephone calls from Kenneth Lay as Enron began its collapse, but does not appear to have reacted in any way and did not inform the president.

Mr Lay apparently asked O'Neill to encourage US banks to extend their credit to Enron, but was refused.

The treasury secretary famously described Enron's collapse as the result of the "genius of capitalism". He said there was a price to pay for bad business decisions.

Mr O’Neill was the chairman of the multi-national aluminium company Alcoa. He was previously deputy budget director in the Nixon and Ford administrations, where he worked with both Dick Cheney and Chairman of the Federal Reserve Alan Greenspan.