Karun Saingam, one of the 10, said he wanted to find out whether he and his colleagues would enjoy the same privilege as Thaksin, who he noted had received full salary and benefits while doing no work.

"Should an important matter come up, like the voting on the National Counter Corruption Commission nominees, senators are expected to cut short their leave and vote," he said, adding that Thaksin's return to work last month was seen by many as illegal.

Meanwhile, Two more outgoing senators resigned yesterday increasing the number of upper house alumni who are apparently preparing to run for seats in the lower chamber.

Senators Nipon Wisityuthasart and Somkiat Saralamba submitted their resignations - which take effect today - to the Senate Secretariat.

Nipon, who served as the first deputy Senate speaker, will run as a party-list candidate for the Democrat Party in the next election, a source close to him said yesterday.

Nipon met Democrat chief adviser Chuan Leekpai at the party's headquarters yesterday.

However, when asked about his political future, Nipon said he needed a few days to think about it before deciding.

Somkiat is likely to join the Chat Thai Party, said a Senate member who declined to be named.

Earlier, outgoing senators Nantana Songpracha and Pichet Pattanachote resigned, apparently to prepare to run for seats in the House of Representa-tives.

Their colleague Tawil Praisont will follow suit next week, another source said.

Other caretaker senators said to be thinking about a move to the lower house include Karoon Sai-ngam and Chirmsak Pinthong.