US military chiefs have backed Britain to remain a major military power despite sweeping spending cuts.

Pentagon press secretary Geoff Morrell said in a statement: "We are confident that the UK will continue to have the capacity to provide top-tier fighting forces in Afghanistan and other future missions in defense of our shared interests and security.

"We are pleased that the UK clearly intends to maintain its historical role as a leading nation that shapes global security, and the fourth largest military budget in the world."

The vote of confidence came a day after the Government announced that the Ministry of Defence's £36.9 billion budget will be cut by 8 per cent in real terms over the next four years, lower than the average 25 per cent cuts faced by other departments.

Britain's armed forces review, the first since 1998, calls for a military with fewer people, fewer ships, fewer aircraft, fewer nuclear warheads and a smaller budget.

Senior US politicians, including Secretary of State Hillary Clinton, had voiced concerns that cuts would hamper Britain's ability to help US forces in conflicts worldwide.