Pakistani troops backed by helicopter gunships killed at least 55 Taliban in the troubled Swat valley on Saturday as the government said the military offensive,crucial for the "survival of the country",will continue till terrorists are eliminated. The "full-scale operation" against the Taliban targeted militant hideouts in in Mingora,the main town of Swat as also bases in Matta,Qambar,Ziarat,Mushkomai and Chamtalai areas,the military said in a statement adding that 55 militants have reportedly been killed. With this,the total of number of Taliban militants killed in three days of operations climbed near 200. Fighter jets and helicopter gunships pounded militant positions across the scenic valley located 160 km from Islamabad. The army said the Taliban "are on the run" and accused them of "trying to block the exodus of innocent civilians" and even taking them hostages. The operation will continue till terrorists are eliminated,Prime Minister Yousuf Raza Gilani said. Responding to a question on whether the operation was launched due to international pressure,Gilani said the "this is our own war,a war for the survival of the country and the future of the people. We had no other option." "The provincial government saw the peace deal and the constitution being violated". The militants had gone "against the judiciary,democracy and parliament" and this was tantamount to an "open revolt",Gilani said. Noting that this is "not a normal war" but a "guerrilla war," he said the troops are trying to ensure that there is "minimum collateral damage". Pakistani President Asif Ali Zardari,who is on a state visit to the United States,told a TV channel that "this is war. If they kill our soldiers,then we do the same." Separately,during an interaction with Pakistani-American community,he said "we will not step back. if they want to damage Pakistan,we will fight them for the sake of our country and for the sake of our future generations." The security forces are also conducting operations in Buner and Dir districts,which were taken over by Taliban fighters from Swat. Meanwhile,at least six persons were killed and over 10 others injured on Saturday in a missile strike by a US drone in Pakistan's troubled South Waziristan tribal region today. The drone fired four missiles at a house and an adjacent seminary in Sararogha in South Waziristan Agency,considered a stronghold of the Tehrik-e-Taliban Pakistan led by Baitullah Mehsud. Most of those killed in the drone attack are believed to be militants,officials said. The military said it had destroyed main militant headquarters at Loenamal in Matta,considered a stronghold of the Taliban. Two soldiers were injured in Mingora. The militants are using the homes of civilians to engage the security forces and indiscriminate mortar fire by the rebels in the populated areas of Mingora had resulted in civilian casualties,it said in a statement. The militants are also harassing the civilian population and are involved in looting and arson in Mingora. The statement said there were reports that "criminals who had sided with hard-core militants are now fleeing from the area". The military said troops had also secured several strategic areas in Swat,including ridges on the outskirts of Gulabad and two dominating mountain heights known in Shangla. Two soldiers were injured in operations in these areas. However,the operations in Buner,Dir and Swat have sparked the exodus of almost half a million people displaced by the intense fighting. Officials in Swabi district said around 150,000 people had fled Buner during the last few days. People who fled from Swat to the nearby Mardan district have also said that several civilians were killed by the army's artillery barrages. Gilani said the security forces are trying to prevent civilian casualties and will try to complete the operations as soon as possible. The NWFP government and agencies like the UNHCR and Red Cross have set up relief camps. International agencies have warned that Pakistan could be facing its worst humanitarian and refugee crisis since partition of 1947.