Thousands of civilians have fled Pakistan's northwest Khyber tribal region where the latest military offensive killed 33 more suspected militants Sunday. Pakistan is under intense US pressure to crack down on insurgents along its border with Afghanistan, especially the lawless tribal belt where al-Qaida leader Osama bin Laden is suspected to be hiding. The US believes militants use Pakistan's tribal areas as safe havens from which to plan attacks on Western troops across the frontier in Afghanistan. Khyber is of particular concern because militants frequently attack trucks along the famed Khyber Pass, a main route for supplies destined for US troops in Afghanistan. The military destroyed two training centers and 15 militant homes on Sunday, killing 33 alleged insurgents, a statement from paramilitary forces operating in the area said. Nine more were taken into custody and two people kidnapped by militants were recovered. The region is largely off-limits to journalists, making it difficult to verify the information independently. Farooq Khan, a government official in Khyber, said hundreds of families fled the region since authorities relaxed a curfew Friday. He said security forces were "keeping a strict eye" out for any militants trying to blend in. The Taliban-affiliated group Lashkar-e-Islam is a main target in the latest offensive, which authorities say has killed about 120 alleged militants. The operation was launched a week ago after a suicide bombing at a border checkpoint killed 19 police. Meanwhile, Prime Minister Yousuf Raza Gilani said Sunday that there were indications an attack on Sri Lanka's cricket team in the eastern Pakistani city of Lahore earlier this year was financed from Sri Lanka. Gilani said he was told this by Sri Lanka's President Mahinda Rajapaksa. "He was telling me that, 'We have got some clues, that finances were made from Sri Lanka to Pakistan," Gilani said, referring to a recent meeting with Rajapaksa in Libya. He said Pakistani officials would travel to Sri Lanka to gather clues, "which could lead us to the attackers of the cricket team." The attack wounded several players and killed six police officers and a driver. The most prominent suspect is the banned Pakistani Sunni extremist outfit Lashkar-e-Jhangvi, an al-Qaida ally. Elsewhere, three policemen were fatally shot - each by a single bullet to the head - west of Pakistan's capital. The dead policemen were discovered early Sunday in their guard room along a railway bridge in Hasan Abdal, a town 25 miles (40 kilometers) west of Islamabad, police official Arshad Mahmood said. It appeared to be a targeted killing, he said, but he would not say if Taliban militants were suspected. Pakistani Taliban fighters frequently target police, though usually in the northwest.