Suspected Abu Sayyaf militants killed seven policemen in an ambush Sunday after their comrades shot to death two government soldiers in a separate attack in the southern Philippines, security officials said. Navy Rear Admiral Alex Pama said suspected Abu Sayyaf gunmen opened fire Sunday on a police convoy negotiating a dirt road in far-flung Sumisip township on Basilan island, killing seven policemen. Two other policemen survived the ambush and were taken to a hospital. The policemen were returning to camp in nearby Maluso township after escorting a Basilan town mayor, who has backed recent offensives against Abu Sayyaf militants. The gunmen apparently thought the mayor was in the police convoy when they attacked, Pama said. The gunmen may have wanted to avenge the loss of several fighters during recent marine offensives and the recent escape of a lending company employee, whom the militants have held for months in the hope of getting a ransom payment, Pama said. In a separate attack late Saturday, another group of suspected Abu Sayyaf gunmen killed two unarmed soldiers involved in the construction of a school in nearby Tipo Tipo township, also in Basilan. The soldiers, who belonged to an army engineering brigade, walked off a school construction site to buy cigarettes when they were fired upon, Pama said.