KABUL: An Afghan official says Pakistani forces have crossed into eastern Afghanistan and clashed with Afghan troops. Col. Abdul Hanan, the acting provincial police chief in the eastern Khost province, says the fighting broke out early Sunday and is still underway. He was not immediately able to confirm reports of casualties. The two countries are separated by the 2,400-kilometer (1,500-mile) Durand Line, which was drawn by British rulers in 1896. Kabul does not recognize it as an international border and has objected to new fortifications being built by Pakistan. The two US allies routinely accuse each other of failing to crack down on militants who operate along the porous border. Meanwhile, an Afghan official says insurgents have killed at least four police in an attack on a checkpoint. Arif Noori, spokesman for the provincial governor in the eastern Ghazni province, says five other police were wounded in the attack late Saturday. He says the militants opened fire on the checkpoint and then targeted reinforcements with a roadside bomb. No one has claimed the attack, but the Taliban are active in the area and control large parts of the province. The Taliban stormed a government compound in another part of Ghazni late Thursday, killing 15 people, including three senior local officials.