Democrat Party leader Abhisit Vejjajiva accused the government of Prime Minister Yingluck Shinawatra of undermining economic stability though its populist policies as he launched the debate on the opposition's censure motion in the House of Representatives on Tuesday.
As he spoke, anti-government protesters continued to occupy the Finance Ministry, which is crucial to the implementation of the government's policies.
Mr Abhisit accused Prime Minister Yingluck of being the centre of corruption, alleging she had had abused her authority in a systematic manner - upstream, midstream and downstream.
He focused his attack on her government's rice-subsidy scheme that pays farmers fixed prices for their crops, well above market rates.
He said there were government policies made to accommodate corruption, such as the rice pledging scheme. Many agencies confirmed that the scheme had lost 400 billion baht, but farmers had received less than 200 billion baht in total over the past two years.
"Thailand is no longer the world's rice biggest exporter and we've shown that there are problems in the rice release process," he said, "and the government-to-government deals are fake.
"Those who benefit from the scheme are influential people who are close to the government, but the prime minister has done nothing about this," the opposition leader said.
The rice scheme was a key campaign promise that helped her Pheu Thai Party win the July 2011 general election. It had accumulated losses of 400 billion to 500 billion baht over the past two fiscal years, Mr Abhisit said.
"If you continue this policy for seven years, our public debt will reach 60% of GDP," he said. "And there is now corruption at every level of this scheme."
On the 2-trillion-baht infrastructure loan bill, Mr Abhisit said the government had been trying to avoid inspection of the details after MPs and senators found irregularities in the figures and concluded some of them were doctored.
The government was not telling the truth when it said Nong Khai was one of the destinations for the high-speed train. That line would go no further than Nakhon Ratchasima, he said.
Democrat leader Abhisit Vejjajiva, left, criticises the populist policies of Prime Minister Yingluck Shinawatra's government at a censure debate on Tuesday. (Photos by Chanat Katanyu)
In reply, Prime Minister Yingluck said that her government had been successful in carrying out its policies so far.
"This government came into power when the world economy was at its lowest in four years and that had affected exports of regional countries.
"The government has been speedily addressing economic issues, such as improving people's well-being and raising the GDP following the crisis, and we achieved a 6.5% growth," Ms Yingluck said.
The premier said, "I've always respect the legislative institution, independent organisations and democracy. We have opposing views, but the government has tried to promote public participation and look after the protesters in a peaceful manner."
The government is under attack from street protesters. They have occupied parts of the Finance Ministry to try to paralyse the administration and force the dissolution of parliament.
Demonstrators led by anti-government protest leader Suthep Thaugsuban, a former Democraty Party MP, had occupied the Foreign Ministry Monday night, but left the premises Tuesday morning. He resigned from parliament to head the demonstrations.
A warrant for the arrest of Mr Suthep, who has headquartered himself at the occupied the Budget Bureau, was issued Tuesday.
Political observers saw it as a good sign that Mr Abhisit and the Democrats had attended parliament for the censure debate, instead of resorting to street politics.
"I think by attending the debate, Mr Abhisit is sending a signal to Mr Yingluck that there is room for political dialogue to end the street protests," said Panitan Wattanayagorn, a political scientist at Chulaongkorn University.
"Mr Abhisit and Ms Yingluck must come together and calm down the protests," said Mr Panitan, who was a spokesman for the Democrat-led government during 2009 to 2011.
The government has been the target of mass protests in Bangkok since her coalition pushed a bill to pardon Ms Yingluck's brother Thaksin of a corruption conviction, and grant an amnesty in thousands of other politically related cases during 2004 to 2013.
The bill was rejected by the Senate.
The ruling coalition controls 300 of the 500 seats in parliament, or 60% of parliament seats. The censure motion is expected to be defeated when a vote is held on Thursday.