Security forces killed six suspected Islamic militants and detained seven after a gunbattle in a volatile region in northwestern Pakistan where militants have stepped up attacks in recent days, an intelligence official said Sunday. The fighting broke out late Saturday in North Waziristan after three vehicles, carrying militants and explosives, were stopped at a roadblock manned by army and paramilitary troops, the official said on condition of anonymity because of the secretive nature of his job. When soldiers refused to let the vehicles - a pickup truck and two cars - pass, armed men inside opened fire and troops retaliated, he said. One of the cars blew up when troops shot at it, he said. Six militants were believed to have been killed, and their bodies taken away by fellow fighters, he said. Another seven militants were detained.