Pakistan’s armed forces say they have killed more than 140 militants over the past 24 hours during fierce fighting in the Islamist stronghold of Swat.Having surrounded many towns in the region, the army is now engaged in a full-scale operation to remove the militants on the prime minister’s orders. In a televised address Prime Minister Yusuf Raza Gilani said the army were free to strike at “militants and terrorists” who are trying to hold the country hostage at gunpoint. Under pressure from the United States, the struggle in the northwestern valley has become a test of Pakistan’s resolve to fight a growing Taliban insurgency. Hundreds of thousands of people have been fleeing the area. But as the fighting intensifies, aid agencies say the humanitarian crisis is also getting worse, amid reports of up to half a million people trapped by the fighting. The UN has also expressed extreme concern for children in the area. Some have witnessed violence, many have been forced from their homes, and having gone without sleep for several days, are unable to get medical care.