BANGKOK, March 30 (Xinhua) -- Thailand will build 2,506 km high-speed railways linking northern Chiang Mai, northeastern Nong Khai, southeastern Rayong and southern Padang Besar with the capital by 2036, a Thai official said.

Suphalerk Soodyodprasert, Rail Project Development Officer from the Office of Transport and Traffic Policy and Planning (OTP) under Thai Ministry of Transport, introduced the development of high-speed railways in Thailand Thursday at the Rail Asia Expo & RISE Symposium.

The first phase of Bangkok-Nong Khai high-speed rail, Thailand's first high-speed railway under Thailand-China cooperation, is under construction after a ground-breaking ceremony late last year, Suphalerk said.

He also introduced Thailand's master plan of high-speed railways.

The four projects in the first period from 2017 to 2021 include a 253-km first phase of China-Thailand cooperation project, or the high-speed rail between Bangkok and Nakhon Ratchasima, a 355-km second phase from Nakhon Ratchasima to Nong Khai on the Thai-Lao border, a high-speed rail linking Suvarnabhumi, Don Mueang and U-Tapao airports and its further extension to Rayong, and a 380-km Bangkok-Phitsanulok high-speed rail, according to Suphalerk.

He added that a 211-km Bangkok-Hua Hin high-speed rail has been put into the second period of plan, which lasts from 2022 to 2026.

A 288-km high speed rail from Phitsanulok to Chiang Mai is also planned in the second period.

For the third period from 2027 to 2036, Thailand plans to extend the Bangkok-Hua Hin high-speed railway by 424 km to Surat Thani and then another 335 km to Padang Besar on the Thai-Malaysian border.

The master plan is set to cost some 1.57 trillion baht (about 50 billion U.S. dollars).