Velupillai Prabhakaran of the Liberation Tigers of Tamil Eelam said the disaster led to a change of plans.
"The Ranil Wickremesinghe and the successor Chandrika (Kumaratunga) governments were trying to trap the LTTE in an international net and throw it into political venom," Prabhakaran said, according to the Hindustan Times newspaper reported Tuesday.
"Faced with the meaningless absurdity of living in the illusion of peace, we decided to resume our national liberation struggle," he said.
The rebel leader said it was at then that the tsunami struck.
"In these circumstances, our liberation movement was geared to confront the crisis. Our fighting formations, as well as our cadres belonging to various social and administrative services, were immensely engaged in the task of relief and rehabilitation," he said.
Tamil rebels have been waging an armed struggle in the island country for the past two decades. Rebels entered a cease-fire agreement with the Sri Lankan government, giving them time to find a permanent solution to the ethnic problem.
The LTTE chief also extended a hand of friendship to the new president of Sri Lanka, Mahinda Rajapakse.
"I welcome Mr. Prabhakaran's remarks yesterday (Sunday) recognizing my pragmatic approach and my invitation for talks," Rajapakse said.
"We can resume work immediately on reviewing the operation of the cease-fire, whilst preparing ourselves for eventual substantive talks leading to a lasting solution," he said.