KHOST (Agencies) - NATO and US troops killed dozens of militants on the Afghanistan-Pakistan border, officials said Tuesday, after the foreign forces suffered their deadliest month since the fall of the Taliban. US-led helicopters and bombers killed 33 insurgents in eastern Khost province late Monday, while NATO soldiers in the same area cooperated with Pakistani troops across the frontier to kill several more rebels, they said. In Khost, the US-led coalition said it launched air strikes after spotting rebels armed with rockets and heavy weapons massing about eight kilometres from the Pakistan border. "After positively identifying the militants, coalition forces engaged with them using attack helicopters and close air support bombers, killing approximately 33 militants," spokesman Lieutenant Nathan Perry told AFP. Separately an outpost of NATO's International Security Assistance Force (ISAF) in troubled Khost came under attack late Monday from rebels using rockets and small-arms, an ISAF statement said. ISAF, co-ordinating with the Pakistan military, responded with air strikes, artillery and rocket fire, causing the militants to flee into Pakistan, it said. The statement said a number of militants were killed but did not specify how many. An ISAF source however said that 11 rebels were believed to have died. The joint operation comes despite growing tensions between Pakistan and western nations with troops in Afghanistan, and less than a month after US forces allegedly killed 11 Pakistani troops in an air strike. Meanwhile, four persons were killed during a shootout between two rival groups over a petty dispute at Pai-Abizar area in Tank district on Tuesday, the police said. The clash erupted when Saeedullah Khan group allegedly started firing at Miran Shah group after failure of talks to settle a goats' theft clash. Resultantly, Saeedullah Khan and Salim Khan died on the spot. The killing infuriated relatives of Saeedullah Khan who chased the fleeing accused Zarman Shah and Miran Shah by intercepting them in Abizar area where the exchange of fire took place. During firing which continued for quite some time Zarman Shah and Miran Shah were killed. Police after registering the case have started investigation. Meanwhile, troops demolished two buildings used by militants in the Khyber tribal district on Tuesday on the fourth day of an operation against rebels there, officials said. Security forces blew up an empty building used as a local headquarters of the Lashkar-e-Islami in the Khajoori area, a security official told AFP on condition of anonymity. The building was previously the residence of Lashkar-e-Islam's founder, Mufti Munir Shakir. "No one was injured or arrested as the building was completely empty when blown up through dynamite," he added. Separately Lashkar-e-Islam followers attacked the empty house of a religious leader who was a rival of LI's chief, Mangal Bagh, in the town of Pir Killay near the Afghan border, the officials said. Troops moved the LI men away but they dynamited the house, which belongs to Pir Saifur Rehman, head of the Taliban-linked Ansarul Islam group, the officials said. Bagh's own house was blown up by troops on Saturday. Both Bagh and main organisation of Taliban militants have denied that he is linked to the Taliban. Meanwhile, unknown men blew up an under-construction checkpost of the security forces with the help of explosive material in Wana, while in district Tank, four persons including two dacoits were killed in exchange of firing. BBC while quoting the political administration told that some unknown men have installed explosive material next to the boundary wall of the checkpost of security forces at night and the checkpost was completely destroyed as the result of the explosion.  No loss of life was reported in the blast. Meanwhile, four persons including two dacoits were killed in the exchange of firing between the local people and the dacoits in district Tank. The police in Tank said that some notorious dacoits opened firing on villagers when they were trying to take animals. According to police, two persons identified as Saif Ullah and Salim were killed on the spot while in the attack of the villagers, two dacoits were also lost their lives. The people of Tank opined that the incidents of criminal activities were reduced after the introduction of local Taliban in Tank. Besides, many criminals were killed by bullet shots in South and North Waziristan. Meanwhile, the law and order situation and ever-increasing activities of the criminals and law-breakers in Peshawar and surrounding areas had necessitated action against criminal gangs. Tehsil Bara of Khyber Agency had become a sanctuary of criminals which virtually paralysed the political administration, and its writ was being diminished. Innocent people were suffering at the hands of these criminal elements, as they were also involved in extortion, kidnapping for ransom, dacoities and other social evils, forcing FATA Administration to move against outlaws in Khyber Agency, and which ultimately initiated action against criminals in Bara Khyber Agency. The criminals had also started forays in the settled areas of Peshawar, which instilled a sense of insecurity in its residents. Therefore simultaneously Provincial Government of NWFP initiated action in Peshawar, with police raids conducted in Peshawar arresting 46 criminals recovering arms, ammunition and narcotics from their possession. Before initiating the action, extensive consultations were undertaken at various levels and between the Federal Government, FATA Secretariat and the Provincial govt. The action, which started on June 28, 2008, has been termed as a purely a law enforcement action conducted by the civil govt through Frontier Corps in Khyber Agency and Police and Frontier Constabulary in settled areas, and Army was no way is involved in this action. Interior Ministry has reiterated once again that the action was purely against the criminals who were causing extreme hardship to the residents and endangering the security of the area. It has been announced that the basic purpose of restoring normalcy and law and order has been achieved with minimum damage and without any collateral losses, and the action will continue until all laid down objectives are achieved.