The Central government on Sunday called off its truce with the United Liberation Front of Assam even as the army prepared to resume operations against the outlawed group's strongholds in the state.

The decision to end the ceasefire -- announced on August 13 and subsequently extended several times -- was taken in view of continued violence and extortion by ULFA cadres, Union home ministry officials said.

The last extension of the truce ended on September 20 and the Centre had held off from resuming army operations against ULFA to give the group some more time to provide a written commitment about joining direct talks, they said.

However, the government's efforts to pursue the peace process will continue, the officials said.

Meanwhile, army officials said columns had been moved to launch operations against ULFA strongholds in Tinsukia and Jorhat in upper Assam and in Nagaon, Barpeta and Darrang in lower Assam. The resumption of operations against the ULFA, top army officials said, was aimed at preventing its cadres from re-grouping.

"Operations are being launched as ULFA cadres are continuing to hit soft targets by killing and abducting tea gardens officials and targeting government installations," said an army official.

The ULFA had initially responded positively to the peace overtures, but recent weeks have seen another spurt in violence blamed on its cadres. ULFA members shot dead a tea garden manager on Saturday in Tinsukia district after his employers reportedly failed to meet an extortion demand from the group for Rs 10 lakh.

Following the expiry of the ceasefire on September 20 midnight, two rounds of deliberations were held between National Security Advisor M K Narayanan and Home Secretary V K Duggal to review the situation in Assam.

The government had warned ULFA that military operations will be resumed if did not give a written commitment on joining peace parleys. The army too had been opposed to the extension of the truce. The peace process had hit a road-block due to ULFA's insistence that five of its top leaders held in jail in Assam should be released before any talks were held.

Noted Assamese author Indira Goswami, a key mediator between the ULFA and the government, said she had been informed by the National Security Advisor that the peace process would continue despite the withdrawal of the truce.

"National Security Advisor Narayanan told me that though the ceasefire has been called off, the peace process will continue. He said the moment the government receives a written commitment from the ULFA, it will review the situation and take appropriate action," she said.

Arup Borbora, the spokesman of the ULFA-nominated People's Consultative Group that has held several rounds of parleys with the Centre, said the body had met on Saturday in Guwahati to review the situation but the discussions were inconclusive.

"We are going to meet again to frame our future course of action," Borbora told PTI on phone from Guwahati.