PESHAWAR // A suicide bomber killed at least 27 people outside of a hospital crowded with Shiite mourners in northwest Pakistan today, according to local police. The Pakistani Taliban claimed responsibility for the blast in Dera Ismail Khan, saying it was targeting security forces, two police were among the dead. But others said the motive appeared to be sectarian, noting the area has experienced much friction between Sunni and Shiite Muslims. Violence in northwest Pakistan is a major test for the coalition government led by the party of assassinated former prime minister Benazir Bhutto, especially after the resignation of former army chief Pervez Musharraf as president yesterday. The bomb went off outside a hospital in Dera Ismail Khan, 280km South-west of Islamabad, as Shiite Muslims were mourning and protesting against the killing of a leader. Gunmen shot the leader earlier and his body had been taken to the hospital. The attack also came as more killings were reported in a northwest tribal region where military clashes with insurgents have reportedly killed hundreds and spurred threats of militant revenge. Mohsin Shah, a top district official, said sectarian conflicts have spawned several targeted killings in recent weeks. Mr Musharraf oversaw security after he threw Pakistan's support behind the US-led campaign against terrorism. His departure has raised questions about the government's commitment, even though it has made security a priority. The United States and other allies are keen to see Islamabad turn its attention to security and pressing economic problems now that the controversy over Mr Musharraf is out of the way. Since July last year, Pakistan has suffered a wave of militant violence in which hundreds of people have been killed, including many security forces members. Violence subsided after the coalition government came to power in March and opened talks with militants. But the lull ended and militants stepped up attacks after their top leader, Baituallah Mehsud, suspended talks in June. Photographer Mustansar Baloch was slightly wounded in the blast at the hospital as he was covering the protest. "I couldn't see or hear anything for some moments after the blast but then I saw bodies lying on the ground and the wounded were screaming," Mr Baloch said. Separately, Pakistani security forces killed at least 20 Islamist militants in a clash in Bajaur tribal region, a known sanctuary for al Qa'eda and Taliban militants on the Afghan border, a government official said. The fighting erupted about 25 kilometres east of Khar, the main town in the region, yesterday evening after militants attacked several security checkposts. "The exchange of fire lasted for about nine hours and we have reports that at least 20 militants were killed," Mohammad Jameel, a senior government official in Bajaur, told reporters. Heavy fighting erupted in Bajaur early this month when Pakistani Taliban militants attacked a security post. According to government estimates, about 170 people have been killed while about 100,000 villagers have fled the region. *Reuters