"I haven't spoken directly to Thamarak, but his aide expressed puzzlement about the rumours," she said. Sudarat said she was confident Thamarak would not leave the party, adding that he could clear himself of all charges relating to the alleged funding of small parties to lend the April 2 vote an air of legitimacy.

"The ruling party has no need to prepare any contingency plan for Thamarak because justice will eventually prevail," she said.

She also said she had instructed party members to stop verbal attacks on their opponents, asking them to heed the recent royal advice on unity.

A party official said speculation had snowballed because Thamarak did not attend a party meeting early this week.

"Thamarak informed the party of his leave and some people might have misunderstood his absence as proof he had resigned," the official said on condition of anonymity.

A source said Thamarak would not comment on the matter, for fear of fuelling further rumours.

Meanwhile, party deputy secretary-general Pongsak Ruktapongpisal yesterday said reporters should have spoken with him before filing reports about his alleged departure from the party.

Pongsak faces the same charges as Thamarak - that he played a role in bankrolling small parties for the election - and is rumoured to be planning to leave Thai Rak Thai as well.