Karat said told the party-backed Kairali TV channel: "Achuthanandan has been included in the central committee because he was given consideration as a special case.
"Generally people who are above 80 are included taking into consideration their long experience in the party," said Karat.
The Communist Party of India-Marxist Monday formed a new 15-member politburo and an 89-member central committee. The veteran Achuthanandan was not included in the politburo.
On Monday, Achuthanandan, now the leader of the opposition in the state assembly, did not attend the customary public meeting of the CPI-M at the end of the party congress.
Karat said: "Achuthanandan never boycotted the public meeting. He left after taking part in the congress."
Posters expressing solidarity with the Marxist veteran have appeared in the northern districts of the state.
Kozhikode (Kerala): CPI-M general secretary Prakash Karat Tuesday dismissed as baseless reports that former Kerala chief minister VS Achuthanandan was "ousted" from the politburo.
First Published: Tuesday, April 10, 2012, 15:22