This is likely the last no-confidence vote that Prayuth's government faces before its four-year term ends next year. The debate is scheduled for four days, with the lower house to vote on Saturday.

Analysts said Prayuth, who has survived three earlier no-confidence votes, is expected to prevail again as his coalition government has a parliamentary majority.

Kicking off the debate on Tuesday, the opposition Pheu Thai leader Cholanan Srikaew blamed the government's mismanagement for broadening the gap between rich and poor, and leading Thailand to take a step backward economically.

He also accused Prayuth of ignoring corruption in government agencies and increasing unnecessary public debts to support his populist policies.

"Thailand is a coma patient," Cholanan said.

"It is overwhelmed with debts because of this government."

In defence, Prayuth said his government has successfully steered the economy and handled the COVID-19 pandemic over the past two years.

"We are able to reopen the country, generate income and resume the economy," Prayuth said.

"We can prove it with the numbers."

Prayuth came to power in a 2014 coup before winning a general election in 2019 and becoming prime minister, backed by the ruling Palang Pracharath Party, though it is roiled by internal rifts.

It sacked its controversial Secretary-General Thammanat Prompao and 20 other Parliament ministers last year, who later joined the newly-established Thai Economic Party.

The coalition government has 253 parliamentary seats, in contrast to the opposition's 224. Each of the targeted Cabinet members must get at least 239 votes to survive.

In conjunction with the debate, anti-government protesters are camping outside parliament. Organisers have vowed to stage activities, including their own no-confidence vote, to pile pressure on lawmakers to vote Prayuth out of office.

Australian Associated Press