ISLAMABAD (Agencies) - Up to 600 militants from Afghanistan attacked several border villages, triggering shootouts with local militias in which at least four people were killed Wednesday, officials said, the latest in a campaign of large-scale raids on civilians and security forces. Militants stormed the border villages of Nusrat Dra and Kharo in the Upper Dir region, fighting soldiers and pro-government tribal militia. They also set ablaze a government school. According to reports from the two villages, between 550-600 militants launched the attack at around 5 in the morning and the fighting continued for several hours, police official Abdul Sattar told Reuters. Paramilitary troops and police were sent to the villages to help tribal militias there who were trying to fend off the insurgents, local police official Gul Fazal Khan said. The security forces killed three militants and captured three others during the fighting, said Ghulam Mohammed, a top government official in Upper Dir. Four members of the militia fighting the militants were also. Pakistan says more than 55 soldiers have been killed in several attacks from across the border over the past month. The raids have raised tension between the neighbours as they battle protracted insurgencies by Taliban and al Qaeda-linked militants. Pakistani Taliban fighters who fled to Afghanistan in the face of army offensives have joined allies in Afghanistan to regroup and threaten Pakistans border regions again, analysts say. Pakistan blames Afghanistan for giving refuge to militants on its side of the border, leaving its troops vulnerable to counter-attack when it chases them out of the tribal areas and into Afghanistan. Hundreds of militants staged a similar cross-border attack against villages in Upper Dir on June 1, sparking three days of fighting that killed at least 25 soldiers and three civilians, according to local officials. Meanwhile, Kabul said at least 33 police and five civilians were killed in fighting after Taliban crossed over from Pakistan and attacked a remote region in eastern Afghanistan. Nuristan provincial governor Jamaluddin Badr said about 40 rebels also died in the clashes that follow weeks of tit-for-tat allegations of cross-border attacks that have fanned diplomatic tensions between the two neighbours. Dozens of rebels crossing the border from Pakistan triggered the fight, Badr said, attacking police posts in the Kamdesh district of Nuristan. The report we have now from the area is that 33 border police and five civilians, two of them women, have been killed, he said. He said most of the dead rebels were Pakistan Taliban. The bodies of some of them remain in the area and a clean-up operation is under way right now, he said.