BANGKOK (REUTERS) - The panel appointed by Thailand's military government to draft a new constitution after the previous one was torn up following a May coup sought to allay growing criticism on Monday amid calls for more public involvement.

Critics, including politicians from both sides of the political divide, are calling for more public participation and for a referendum to approve or reject the draft charter.

Among the more contentious points is a proposal to make Thailand's 200-member upper house Senate unelected.

The prime minister will also no longer have to be an elected lawmaker, changes critics say are designed to limit the power of elected politicians and ensure that ousted prime minister Thaksin Shinawatra and his allies, which have won every election since 2001, can never return to power.

Thailand's 36-member Charter Drafting Committee (CDC) was handpicked by the junta following the May 22 coup which overthrew the elected government of Thaksin's sister, former prime minister Yingluck Shinawatra.

Bowornsak Uwanno, a law academic who heads the committee, said it was ready to listen to public criticism.

"We are still drafting the constitution. If there is any part that worries society then the committee is ready to listen," Bowornsak told reporters. "There is time until the end of March. We will introduce the draft in April. Don't worry yet."

The draft will be sent to the junta-appointed National Reform Council and Thailand's interim parliament, known as the National Legislative Assembly, for approval.

The army seized power in a bid to restore order after months of political infighting and street protests that killed nearly 30 people. It scrapped a 2007 charter and rolled out an interim constitution that gave the military sweeping powers.

Thailand has been divided for over a decade between Thaksin and his powerful family and the Bangkok-based royalist and military establishment, which sees him as a threat.