AN AMERICAN military aide was given unprecedented access to UK defence plans and took part in the review which saw Harrier jump jets and HMS Ark Royal axed.
The official from Barack Obama's Department of Defense was seconded to the MoD team drawing up plans to cut 42,000 armed forces jobs by 2015.
Labour said it was the first known time that an American had been let in on such sensitive details.
Shadow defence secretary Jim Murphy said: 'It's crucial to talk to our closest ally but it's a surprise to find someone from the US embedded throughout.
'People might feel the US government knew more about the defence review than the British Parliament.' Tom Watson, a former Labour defence minister, raised concerns that information would have been leaked to US defence firms who rival British companies like BAE Systems for defence contracts.
The MoD said it had a long-standing swap deal with the US. A spokesman said: 'Security checks took place prior to secondment.'