This would include establishment of a government in exile for Thaksin on Cambodian soil.

Pheu Thai MP Jatuporn Prompan said the military option was suggested in a confidential paper Foreign Minister Kasit Piromya sent to Prime Minister Abhisit Vejjajiva on November 16 as a guideline for handling the conflict with Cambodia in a worstcase scenario.

"Preparation of a military option is equivalent to preparing for war against Cambodia," Jatuporn said.

"The end game is the normalisation of relations rather than regime change," Jatuporn quoted Kasit as saying in the leaked paper.

The paper called Thaksin "a major threat to the government". The fugitive expremier is using a twopronged strategy to topple the government: cooperation with Hun Sen and activity by the Democratic Alliance against Dictatorship.

Thailand has already employed several diplomatic measures against Cambodia since Hun Sen appointed Thaksin as his and the Cambodian government's economic adviser. The two countries downgraded relations in late October, Thailand scrapped a maritime deal with Cambodia, and Phnom Penh rejected Bt1.4 billion in loans from Thailand.

Cambodia has also rejected Thai demands to remove Thaksin from his position and extradite him to Bangkok.

Jatuporn said the Pheu Thai Party obtained Kasit's confidential paper from a Foreign Ministry official. He distributed it to reporters during a press conference at party headquarters.

The paper suggested the government to get rid of the "major threat" (Thaksin) and bring an end to cooperation between Thaksin and Hun Sen.

It listed three possible scenarios in the diplomatic row between the two countries. Thailand could prevent Thaksin and Hun Sen from worsening the situation simply by refusing to respond to them and trying to find an influential figure or country able to persuade Cambodia to back down.

Second, if the conflict does increase in intensity, the Thai government would step up retaliation while remaining sensitive to its effect on ordinary people and the national interest.

Third, in the worst case, such as a violation of Thai sovereignty or anything resembling the establishment of a government in exile for Thaksin, Thailand would cut diplomatic relations and resort to using military force.

Meanwhile, the Foreign Ministry yesterday would not deny the existence of the document and its content but said it would set up a committee to find whoever leaked the document to the opposition party.

The ministry will consult the Office of the AttorneyGeneral about taking legal action against Jatuporn under the Information Act of 1997, said ministry deputy spokesman Thani Thongpakdee.