AMMAN - Syrian authorities on Monday blamed Islamist militants for the massacre of 108 men, women and children in the town of Houla and denied UN and witness accounts that army tanks were in the area at the time.In a letter to the UN Security Council published by state media, the Foreign Ministry said the Syrian army had clashed with hundreds of armed men who it said committed Friday's massacre. The ministry said the killers used knives, which it called a "signature" of Islamist militant attacks.It said three Syrian soldiers were killed and 16 wounded.United Nations Secretary-General Ban Ki-Moon said in a letter to the Security Council on Sunday that UN observers who visited the site after the massacre "saw artillery and tank shells and as well as fresh tank tracks", adding that many buildings had been destroyed by heavy weapons.Witnesses and opposition activists said Assad's forces, the only side with artillery and tanks during the 14-month-old uprising against his rule, carried out the massacre of the Sunni Muslim civilians. They said the 108 were mostly killed by bullets and knives but that at least 15 also died from shelling.Houla is mostly populated by Sunni Muslims - from Syria's majority community which has led the revolt - while many of the surrounding villages are dominated by Alawites, the offshoot of Shi'ite Islam that provides most of Assad's ruling cadre."Not a single tank entered the region and the Syrian army was in a state of self-defense using the utmost degree of self control and appropriate response, and anything other than this is pure lies," the ministry's letter said."The terrorist armed groups ... entered with the purpose of killing and the best proof of that is the killing by knives, which is the signature of terrorist groups who massacre according to the Islamist way."