LONDON (AFP) - British lawmakers warned Wednesday that cuts to the defence budget, including scrapping aircraft carriers, planes and 17,000 troops, could leave the armed forces unable to fulfill key tasks within four years. In a stinging report, the cross-party House of Commons defence committee challenged Prime Minister David Cameron's assertion that Britain will retain a "full spectrum defence capability" despite the cuts. "We are not convinced, given the current financial climate and the drawdown of capabilities arising from the Strategic Defence and Security Review, that from 2015 the armed forces will maintain the capability to undertake all that is being asked of them," said the report. "Given the government's declared priority of deficit reduction we conclude that a period of strategic shrinkage is inevitable." Cameron's Conservative-Liberal Democrat coalition claims it was left a 38-billion-pound (61.9 billion dollar, 43.6 billion euro) "black hole" of unfunded defence spending commitments when it took office in May last year. The SDSR in October set out plans to reduce the size of the army, navy and air force by a total of 17,000 troops, cancel the Nimrod MRA4 reconnaissance planes and withdraw early the aircraft carrier Ark Royal and Harrier jump-jets. The government has insisted Britain would still be a global player after the cuts, and said arrangements with allies such as France would help make up any shortfall. However, the report questioned this claim and said a new National Security Strategy was in danger of becoming a "wish list" without more resources. "The prime minister's view that the UK currently has a full spectrum defence capability is rejected by the committee," the report said. It said that under current plans, the armed forces will be continually operating at full capacity, leaving little leeway to deal with unexpected events, particularly while 9,500 troops are deployed in Afghanistan. The government's decision to join a bombing campaign against Libya earlier this year suggests it has "postponed the sensible aspiration of bringing commitments and resources into line", it added. Committee chairman James Arbuthnot, a lawmaker from Cameron's Conservative party, said: "This is a clear example of the need for savings overriding the strategic security of the UK and the capability requirements of the armed forces." Cameron angrily rejected the earlier criticism by military chiefs in June, after they said Britain would be overstretched by Libya, saying: "Look, tell you what, you do the fighting, and I'll do the talking." And on Wednesday, Defence Secretary Liam Fox insisted that managing Britain's record budget deficit was a "national security imperative". "We continue to have the fourth largest military budget in the world and the SDSR has put defence back on a stable footing," he said, adding: "I am pushing through radical reform to ensure that the mistakes of the past are not repeated." General David Richards, the head of the armed forces, added: "We have had to take some tough decisions, but... we will remain a formidable fighting force on the world stage. "We will remain capable of sustaining our operations in Afghanistan and Libya before re-balancing will give us the flexibility to maintain our ability to project power across our spheres of interest."