(Recasts with updated toll in new violence) By Biswajyoti Das GUWAHATI, India, Jan 6 (Reuters) - Separatist rebels triggered an explosion in India's restive northeastern state of Assam on Saturday, killing seven people and taking the toll in a wave of coordinated overnight violence to 55, police said. The attacks have been blamed on the United Liberation Front of Asom (ULFA), which has been fighting for an independent homeland for Assamese people since 1979. In the latest strike on Saturday night, rebels blew up a government vehicle with an improvised explosive device killing seven people, four of them policemen, in Diphu town -- about 270 km (170 miles) south of Guwahati, the state's main city. Police said the chain of violence began late Friday night when heavily armed ULFA guerrillas gunned down at least 32 people -- mostly brick kiln workers and traders -- in the state's eastern district of Tinsukia. A further 15 labourers, including a woman, were killed in two strikes in adjacent Dibrugarh district. Another person was killed when militants triggered a blast in Sivasagar district. Police said the violence was an attempt to intimidate people after an independent opinion poll by a peace group in nine districts of the oil and tea producing state showed 90 percent of the people rejected the ULFA's separatist demands. The attacks forced the authorities to step up security across Assam. "Anti-insurgency operations will be intensified," Tarun Gogoi, Assam's chief minister, told Reuters. Authorities clamped a round-the-clock curfew in Tinsukia after thousands of angry residents came out on the streets protesting the failure of the security forces to provide safety. Most of the victims were migrant labourers from the eastern state of Bihar who have been attacked by the rebels in the past to attract the attention of the federal government, security officials said. VICTIMS TIED UP "There were about 10 militants in each group and they attacked the labourers when they were preparing their dinner," said V.K. Ramisetti, a senior police official in Dibrugarh, referring to one of the attacks. "Witnesses told police that attackers came with their faces covered, and they tied the hands and legs of the victims before they were shot dead," another police officer, requesting anonymity, told Reuters. The three districts that witnessed the attacks had not been polled on the separatism question, but were to be included in the second phase. The ULFA has described the poll as a conspiracy of Indian intelligence officials. "Such an exercise is meaningless and fruitless," ULFA chairman Arabinda Rajkhowa told Reuters by telephone. "No referendum or opinion polls can be conducted without our consent and the supervision of credible international agencies." No group has claimed responsibility for the attacks, but police and security analysts say the ULFA was behind the killings. The attacks came a day after Indian officials appealed to the ULFA not to disrupt national games next month which the rebels have threatened to disrupt with violence. The nearly three-decade-long insurgency in Assam has killed more than 20,000 people.
