Agartala, March 10 :    Agartala, March 10:  Seven National Liberation Front of Tripura (NLFT) militants were gunned down by the Assam Rifles today at Kolacherra under Bhangmun police station in North Tripura district. The encounter has been dubbed as one of the biggest in recent times. The jawans recovered two AK-47 assault rifles, five Chinese assault rifles and large quantities of ammunition from the slain militants. Official sources here said the Army and the Assam Rifles had launched a special cordon and search operation last night to flush out tribal militants hiding in the remote areas of Kanchanpur subdivision bordering the Chittagong Hill Tracts of Bangladesh. Sources said nearly 80 militants had assembled in the area to move to a new hideout. While combing the forests, the Assam Rifles patrol was attacked by NLFT rebels at Bhangmun. In the encounter which lasted over two hours, security forces killed seven NLFT rebels. The slain militants are yet to be identified. Shortly after receiving information, deputy-inspector general, Assam Rifles Brig. B.K. Panwar rushed to the spot to oversee operations. Sources said the Assam Rifles and the Army have launched a fresh counter-insurgency operation codenamed ?Synergised Operation?? to wipe out rebel camps. The long-term operation will cover all the areas under the operational ambit of the Army and the Assam Rifles. Meanwhile, in a similar operation, the Bangladeshi Army demolished an NLFT camp at Thanguan in the Chittagong Hill Tracts and hounded out the rebels on March 5. The seven militants slain this morning had reportedly sneaked into the country through the remote Kolacherra area on March 6 after their camp was busted. Sources said if the Bangladesh government continued with its counter-insurgency drive, it would be easier for security forces to tackle militancy. Meanwhile, the police arrested four tribals this morning in connection with the attack on a passenger jeep at Moharani in which one person was killed and five others injured. Orissa papers leaked: Question papers of at least two subjects in the 1999 high school certificate examination, conducted by the Board of Secondary Examination (BSE), Orissa, have been leaked. Examinations began in the state today. BSE sources said the leak came to light after the headmaster of the Biramitrapur High School and centre superintendent Birendra Kumar Nayak found the seal of the iron chest containing the question papers broken in his office on Tuesday.