More than 30 US politicians, among them seven members of a defence procurement committee, are being investigated in congressional ethics inquiries into influence-peddling, according to a document leaked accidentally on to the internet.

The disclosure sheds light on a process by which billions of dollars a year are spent on defence projects that the Pentagon does not want and which limits funds available for US military operations in Iraq and Afghanistan.

House Representatives named in the document include John Murtha, the chairman of the House Defence Appropriations Sub-committee, who