The message was conveyed to Prime Minister Yingluck Shinawatra by visiting Chinese premier Wen Jiabao during a meeting at Government House yesterday.
Chief of the Ministry of Foreign Affair's East Asia Department Damrong Kraikruan said China has sent a proposal to the government for consideration.
PM Wen reiterated his country's plan to join international firms in bidding for the project and expressed hope the contest would be transparent and fair.
Thailand has plans for two high-speed railway lines to Chiang Mai and Nong Khai but has yet to set bidding conditions for the multi-billion dollar plan.
Many other countries have also expressed an interest in competing.
The Bangkok-Nong Khai railway will link to Laos, to a Laotian line that will continue to the Chinese border by 2018, making the line an appealing logistical instrument.
The Chinese leader arrived in Bangkok on Tuesday night for a 24-hour visit while en route back to Beijing after having attended the East Asia Summit in Cambodia.
During his stay in Bangkok, the premier presided over the opening ceremony of a Chinese Cultural Centre, the first in Thailand and made a courtesy call to Privy Council president Prem Tinsulanonda (เปรม ติณสุลานนท์), and was granted an audience by His Majesty the King.
Thailand and China yesterday inked four memorandums of understanding on rice, education, development cooperation, and prisoner exchanges.
In a related development, Prime Minister Yingluck yesterday asked Chinese Premier Wen Jiabao that the three pandas living at Chiang Mai Zoo be allowed to stay longer, as the agreement for their care in Thailand expires next year.
Premier Wen reportedly smiled at the request and said he would ask concerned agencies to consider the request. The pandas - Lin Hui, Chuang Chuang and their daughter Lin Ping - sent as a diplomatic gesture from Beijing have become popular in Thailand.
Meanwhile, relevant authorities have expressed belief that the imminent hike in the minimum daily wage will likely cost some people their jobs but the number will be relatively low.
Labor Minister Phadermchai Sasomsap commented yesterday that many industries are facing a shortage of labor, elaborating that there are more than 300,000 vacancies across the country.
The minister was speaking after the Thai Labor Solidarity Committee voiced concern that some employers might lay off their workers before January 1 in a bid to avoid paying higher severance pay. The Bt300 minimum daily wage goes into effect in 70 provinces from the beginning of 2013.
The Labor Minister assured that due to the current labor shortage, employers will be reluctant to lay off workers due to the increased pay rate.