Opposition leader Abhisit Vejjajiva has demanded the government clarify its stance over the contest for the right to organise the World Expo in 2020.

PM's Office Minister Niwatthamrong Bunsongphaisan recently said the government was considering abandoning plans to bid for the chance to host the prestigious exposition in 2020.

He said the investment needed to host the expo, estimated by Kasetsart University to cost the state 70 billion baht, may be too expensive to make the fair worth hosting.

Mr Abhisit said representatives of the Bureau of International Expositions were impressed with Ayutthaya as a potential venue for the exposition.

He called the minister's decision to review the bid "shocking". He said organising the World Expo 2020 would bring tens of millions of visitors to the country, generate huge revenues and boost the nation's reputation.

Investing in infrastructure in Ayutthaya to prepare for the event would also have long-term benefits beyond hosting the World Expo 2020, the opposition leader said.

Mr Abhisit asked if the government intended to pave the way for another country to win the bid.

The previous government, led by Mr Abhisit, had initiated attempts for Thailand to bid for the World Expo 2020 and Thailand announced its intention to compete for the honour at the World Expo 2010 in Shanghai.