India on Tuesday said it has lodged a protest with Sri Lanka over certain "derogatory" remarks by its Army Chief Sarath Fonseka against some Tamil Nadu politicians and Colombo has expressed "regret".

India's High Commissioner to Sri Lanka Alok Prasad took up the matter "strongly" with Sri Lanka's Defence Secretary Gotabaya Rajapaksa, External Affairs Ministry spokesman Vishnu Prakash told reporters in New Delhi while commenting on remarks by Fonseka in an interview where he referred to some politicians of Tamil Nadu as "political jokers".

"The Defence Secretary of Sri Lanka promised to look into the matter and conveyed regrets should any such comment have been made," Prakash said.

Fonseka had said that the Indian Government would never influence Sri Lanka to restore the ceasefire with the LTTE and it would not listen to the "political jokers" of Tamil Nadu whose "survival depends on the LTTE".

"If the LTTE is wiped out, those political jokers like (Tamil Nationalist Movement leader) P Nedumaran, Vaiko and whoever who is sympathising with the LTTE will most probably lose their income from the LTTE," Fonseka was quoted as saying.

Meanwhile, MDMK chief Vaiko asked the Centre to demand an "unconditional apology" from him.

Vaiko, who has strong views on the ethnic Tamils issue, took strong objection to Gen Sarath Fonseka describing politicians from the state as "political jokers".

The MDMK leader also shot off a letter to Prime Minister Manmohan Singh and said that the Centre should seek an explanation from Sri Lankan President Mahinda Rajapakse for the remarks.

"In a democracy, Army generals do not make such criticism about leaders of a foreign country. This is an unprecedented humiliation for the Indian government and its people by the chief of the Sri Lankan army," he said in the letter.

Fonseka's remarks came days after the Centre agreed to send External Affairs Minister Pranab Mukherjee to Sri Lanka to press for a ceasefire between the forces and LTTE and resumption of dialogue.