The company, known as Planetary Resources, is also backed by space tourism pioneer Eric Anderson, X-Prize founder Peter Diamandis, Ross Perot Jr, son of the former US presidential candidate, and veteran astronaut Tom Jones.

BBC: Plans for asteroid mining emerge

Labour MPs who voted for the war and who are now expressing severe doubts over the US request include such senior figures as Sir Gerald Kaufman and once-supportive backbenchers including Eric Illsley, Geraldine Smith and a host of others.

BBC: Analysis

The plan was unveiled by US Attorney General Eric Holder and by Victoria Espinel, the administration's Intellectual Property Enforcement Co-ordinator.

BBC: White House vows to fight trade-secrets theft