LONDON (Reuters) - The British-led NATO force in southern Afghanistan does not have enough troops to carry out its mission and the Taliban show worrying signs of growing stronger, a parliamentary report has found. The report, by the House of Commons Defence Committee, highlighted a series of concerns, from a lack of training for Afghan police and armed forces to an unclear policy on eradicating the country's vast opium poppy fields. But the chief preoccupation was a lack of support from other NATO countries to provide more troops to the 36,000-strong ISAF mission and evidence that violence, including Iraq-style suicide bombings, was growing as Taliban and al-Qaeda-linked insurgents expand their sphere of influence outwards from the south. "We remain deeply concerned that the reluctance of some NATO countries to provide troops for the ISAF mission in Afghanistan is undermining NATO's credibility and also ISAF operations," the bi-partisan committee concluded in its 65-page report. While praising the commitment of Britain's 7,100 troops to the overall mission, the report's authors added: "The Ministry of Defence asserts that the Taliban insurgency does not pose a strategic threat to Afghanistan (but) violence seems to be increasing and spreading to the previously more peaceful provinces in the north and west ... and the capital. "Moreover, civilian casualties undermine support for ISAF and the government of Afghanistan and fuel the insurgency, further endangering our troops and the objectives of their mission." Defence minister, Des Browne, called the report "balanced". He said he also wanted more NATO help and was encouraging allies to offer more support but he denied the situation in Afghanistan had worsened significantly. "We have overmatched them every time they've faced up to us," he said of the Taliban, adding that Afghanistan was a long-term commitment for foreign forces. "Suggesting we should back off and leave it alone is not the answer." INDISCRIMINATE METHODS NATO troops have in recent weeks been accused by senior Afghan leaders of indiscriminate methods, with scores of civilians reportedly killed in a series of NATO and U.S. air strikes in western Afghanistan earlier this month. Military commanders say they do everything they can to target only armed insurgents, but a series of well-documented cases in which civilians have been killed or caught in the crossfire has greatly increased tensions with Afghan leaders and local people, whom troops need to win over. In their analysis, the report's 18 authors said a lack of trust between Afghans and British-led troops was hurting other efforts, including the need to eradicate poppy fields, which now account for 30 percent of Afghanistan's economic output. Opium poppy cultivation has expanded rapidly over the past year, from 104,000 hectares in 2005 to 165,000 hectares in 2006, the report said, with the absence of a clear policy on how to tackle it making it ever more difficult to rein it in. But the authors noted that Britain had stepped up reconstruction in the semi-lawless, Taliban-dominated south, particularly Helmand province, and said that reform of the Afghan National Army was progressing, albeit slowly. The opposition Conservatives were withering about the report, saying it was a "severe indictment of the government's handling of the situation in Afghanistan" and made a mockery of the former defence secretary's claim that "British troops could be in Afghanistan for three years without a shot being fired".