The Sino-Thai railway project with routes from the Northeast to Bangkok and the East will be delayed for about nine months because of questions about construction costs and unfinished surveys.
Transport Minister Arkhom Termpittayapaisith conceded that hurdles remained after a meeting on the project with Chinese authorities at a Bangkok hotel on Friday.
"It cannot be concluded when the construction will begin," he said.
Ministry sources said the construction start was now likely to be pushed back to around July of next year.
Arkhom: "It cannot be concluded when the construction will begin."
The two countries are jointly undertaking planning and construction of an 873-kilometre rail line from Nong Khai province in the Northeast to Bangkok and the eastern province of Rayong.
Mr Arkhom said that Thailand wanted an investment consultant to help it thoroughly scrutinise the project cost, as China intended to base quotations on the prices of construction materials in China.
As well, both sides have some disagreements over designs, routes and financing for the 252-kilometre section from Bangkok via Saraburi to Nakhon Ratchasima province. As well, aerial surveys of potential routes were only 30% completed, the transport minister said.
Friday's meeting was the seventh between Thai and Chinese authorities responsible for the project. The talks are scheduled to continue on Saturday.
A source at the Transport Ministry said that under the circumstances, construction would not be able to start on Oct 23 this year as planned, but would be delayed for about nine months.
China remains a strong supporter of the railway as it sees huge economic benefit in connecting its southern region to the rest of Southeast Asia via Laos and Thailand.