KABUL (AFP) - A Taliban suicide attack on UN staff at a Kabul guesthouse on Wednesday constituted a war crime and will further jeopardise the delivery of humanitarian aid in Afghanistan, aid organisations said. ACBAR, an umbrella organisation for more than 100 non-governmental organisations, said the attack on the Bekhtar Guesthouse highlighted the increasing threat for aid groups operating in the war-torn nation. This attack constitutes a war crime under international humanitarian law, it said in a statement condemning the attack which killed at least six UN staff. Aid organisations and their staff have been subject to increasing numbers of attacks, threats and intimidation, by both insurgent and criminal groups, as well as of other parties involved in the conflict. Deteriorating security conditions continue to jeopardise the delivery of essential humanitarian assistance and threaten the livelihoods of the most vulnerable, it said. In a statement issued in Brussels, Nato Secretary-General Anders Fogh Rasmussen also condemned the suicide attack on the UN staff as proof that the Taliban are an enemy of the Afghan people, and urged them not to be cowed from voting in next weeks elections. The victims of these terrorist attacks were devoted to helping the Afghan people build better lives, Rasmussen said. In targeting them, the Taliban has demonstrated once again that it is truly an enemy of the Afghan people, he said. In a statement issued in Ottawa, Canadian Foreign Affairs Minister Lawrence Cannon urged Afghans to go out and vote in next weeks runoff presidential election despite the cowardly attack on the UN guesthouse. Canada strongly condemns the violent attacks that have occurred today in Kabul, in particular the attack on the United Nations guest house that claimed the lives of several people, including United Nations employees, and injured others, he said. These cowardly acts, less than two weeks before the second round of Afghanistans presidential election, will not deter the international community from supporting Afghans as they exercise their right to vote. We encourage all Afghans to exercise their hard-won right to determine the future of their country by participating in the second round of voting. The European Union also joined the chorus of condemnation of the Kabul attack. Current EU presidency holder Sweden said the bloc was shocked and appalled by this heinous act of terrorism. French Foreign Minister Bernard Kouchner, whose country has more than 2,500 troops in Afghanistan, vowed that Taliban violence would not prevent the presidential run-off from going ahead. The Talibans goal is clear: kill innocent people and terrorise public opinion to prevent Afghanistan getting back on its feet and to disrupt the electoral process that Afghans have bravely put in place, he said. Indian also joined Canada and Nato to flay the Kabul suicide bomb attack and voiced shock and concern over the incident. We are shocked by the dastardly attack on the UN guesthouse in Kabul, Indian Foreign Minister SM Krishna told reporters in the southern Indian city of Bangalore. We convey our deep sympathy to the UN for the loss of life and hope more security measures will be taken to prevent such attacks, Krishna said.