NEW DELHI, Apr 22 : Outgoing Lok Sabha Speaker Somnath Chatterjee Wednesday said he would reply to Communist Party of India-Marxist (CPI-M) chief Prakash Karat "at an apropriate time" for suggesting that personal interest had prompted him to support the Congress-led government during a trust motion last year.

Chatterjee, who was expelled from the CPI-M last year and is not fighting the Lok Sabha elections this time, also denied Karat's allegation that his support was connected to his continuation as speaker.

"My attention has been drawn to a statement made by Karat, in which he has surprisingly imputed certain alleged motives to me for upholding the sanctity of the office of the speaker due to my supposed personal interest, which I strongly deny," Chatterjee said in a statement here.

"I do not wish to make any further comment just now, which may be sought to be construed to relate in anyway to the ongoing election campaign. However, I reserve my right to deal with the same later at an appropriate time," Chatterjee said.

The war of words between the two broke out following Chatterjee's comment that the withdrawal of support by the Left parties to the Congress-led United Progressive Alliance (UPA) government over the India-US nuclear deal was a mistake.

Karat said Monday that the speaker's allegation revealed his "pro-Congress stand".

Karat said: "By admitting his pro-Congress stance, Chatterjee has exposed the moral high ground he took that the speaker is above party politics. His support to the Congress-led government and his continuance as the speaker are interconnected."

Chatterjee was expelled by the CPI-M after he went against the party directive and refused to step down as Lok Sabha speaker during the July 22 trust motion in parliament last year. The Left had decided to vote against the government.