PESHAWAR At least 20 suspected militants were reportedly killed and three others got injured in the US drone attacks in North Waziristan Agency here on Tuesday morning. Unmanned US drone aircraft fired six missiles into North Waziristan, killing at least 20 insurgents. The missiles struck a fortress-like compound and a vehicle in Ghulam Khan village on the border between Pakistan and Afghanistan, some 15 kilometres north of Miranshah, the main town in North Waziristan tribal district early in the morning. Agencies adds: Some of the militants were on foot. They had just returned from Afghanistan when they were hit, an intelligence official in the region said. So far, the death toll is 20. At least 20 militants were killed when US drones fired six missiles on a militant compound and a vehicle, a senior security official said, adding: Militants were using the compound as a training facility. A local intelligence official and another security official in Peshawar confirmed the drone attack and toll. After the strike, militants surrounded the destroyed compound and were searching through the rubble while an excavator dug graves for the dead in a nearby cemetery, local intelligence officials said. More than 220 people have been killed in over 40 US drone strikes since September 3, angering the government, which is facing criticism for acquiescing to the US missile attacks and reprisals from militant groups based in the area. On Monday US Special Envoy for Afghanistan and Pakistan Richard Holbrooke said it was necessary for Pakistan and Afghanistan to find a common strategic purpose to overcome the various insurgent groups in the tribal border areas, which he said were getting closer. The United States does not as a rule confirm drone attacks, but its military and the Central Intelligence Agency operating in Afghanistan are the only forces that deploy the pilot-less aircraft in the region.