Colombo: The threat of the LTTE has not been wiped out and the rebel group is still active overseas, a top Sri Lankan defence official has warned while criticising the opposition for seeking to reduce military presence in the Tamil-dominated north.

"Prabakaran was killed but if anyone thinks that the danger has been wiped out its not true. Those who fled are very active overseas," Defence Secretary Gotabhaya Rajapaksa said at a campaign rally of his brother and incumbent President Mahinda Rajapaksa.

"The threat of LTTE reviving its terror campaign is very real and the country could be plunged back into the dark era of terrorism of the 80s," the defence secretary, who spearheaded the war against the LTTE, said.

"It is with much effort we have been able to maintain national security. So people who seek power by trying to reduce military camps in the north are wrong," he said.

Sri Lanka will go to the polls on January 8. 68-year-old Rajapaksa is seeking a record third term, a move widely seen as an attempt by the president to seek a fresh six-year mandate amid signs of fading popularity

President's campaign alleges that opposition unity candidate Maithripala Sirisena has a pact with the Tamil National Alliance (TNA) to reduce military presence in the north. Sirisena and TNA have both rejected the allegation.

The opposition alliance has also rejected accusations that they would subject Rajapaksa and the government troops to an international investigation over alleged human rights abuses under Rajapaksa regime. Sri Lanka's 26-year civil conflict, which pitted the government against LTTE, ended in 2009.