MDMK on Thursday expelled two dissident MPs of the party, L Ganesan and Gengee N Ramachandran, who defied the party whip and voted in favour of the trust motion moved by Prime Minister Manmohan Singh in the Lok Sabha on July 22.
In a statement, party chief Vaiko said the two MPs have already been removed from their party posts for anti-party activities.
They are expelled from the primary membership for defying the party whip and supporting UPA government during the trust vote, the statement said.
The MPs have revolted against the party leadership for aligning with AIADMK in the 2006 assembly polls and functioned independently after they were removed from the party posts.
Earlier, they approached the Election Commission to declare their group as the real party. But the EC had recently ruled that the party led by Vaiko was the real MDMK.
Their expulsion came after announcement by the party on Wednesday that it would seek their disqualification for defying the party whip.
By expelling them, the party appears to have followed the foot steps of other parties, like the BJP, who had expelled the dissident MPs, without seeking their disqualification.
Party sources said that there was no point in seeking disqualification as it expected Lok Sabha polls in the near future.