The Transport Ministry will submit the first phase of the 603-kilometre high-speed train project to the National Economic and Social Development Board for approval on Thursday.

If approved, the 179.4-billion-baht project for the first phase will be sent to the cabinet for approval in July, a month later than originally planned.

The first phase involves a 252.5km railway linking Bangkok with Nakhon Ratchasima while the second phase runs from Nakhon Ratchasima to Nong Khai (350km).

Transport Minister Arkhom Termpittayapaisith said on Friday the construction would begin in September according to plan.

"The State Railway of Thailand (SRT) will have to review commercial development plans for station areas. We will likely use the PPP model where the private sector is allowed to co-invest, starting with the Pak Chong station, followed by that in Sikhiu district and Muang districts of Ayutthaya, Saraburi, Nakhon Ratchasima, Khon Kaen, Udon Thani and Nong Khai.

"I insist the project is beneficial to Thailand since China is our largest trade partner. The link would support exports and shipments of raw materials and goods while promoting two-way tourism," he said.

Eighty percent of the route will track the existing line while the rest may call for some land appropriation to make the line straight. Some land may be in the areas owned by the Royal Forest Department and mining areas.

"I assure you Thailand alone will operate the line. We also retain the right to develop land along the lines and around all stations. The SRT will own the rights," Mr Arkhom said.

He also appeased the concern about technology transfers, saying this was the priority from the start.

"It has been mentioned since the first round of talks and the draft contract also spells it out. The Chinese will give us construction techniques, know-how about the operation and on-the-job training. Thais will accompany their Chinese counterparts to learn all these," he said.

Although the contract has not been signed, 250 officials from the SRT and 60 others from the Transport and Traffic Policy and Planning Office have been sent to China."

Besides, almost 20 university lecturers are being sent on a study tour in the mainland, he added.

Transport permanent secretary Chartchai Thipnavee said the SRT had been assigned to check safety standards every step of the way and Thai engineers will verify the designs and construction.

Last week, Gen Prayut Chan-o-cha used his authority as chief of the National Council for Peace and Order under Section 44 of the 2014 interim charter to bypass regulations and speed up the project.

While the move got the project off the ground, it has drawn criticisms, mainly the long-term plan and integration of all transport modes, as well as the "one country, two systems" issue since Japan will also build the Bangkok-Chiang Mai line and some of the railways to be built by the two countries will overlap in Ayutthaya, incurring unnecessarily high costs and redundant investments.