China has been steadily pushing rail to connect the world's second-largest economy with its neighbors in Southeast Asia, and it is taking a practical approach to realizing the goal, industry insiders said.

Three lines that link Yunnan province to Southeast Asian nations have been included in China's medium- and long-term railway network plan and preliminary work has begun, according to sources close to China Railway Corp, the successor of the dissolved Ministry of Railways.

According to the plan, the lines start in Yunnan's capital Kunming and will connect Laos, Vietnam, Cambodia, Myanmar, Thailand, Malaysia and Singapore. They constitute the southern part of the ambitious Trans-Asian Railway that was initiated in the 1960s and began to take shape after 18 countries signed an agreement on the rail network in November 2006.

The huge network aims to provide a continuous 14,000-kilometer rail link between Singapore and Istanbul in Turkey, with possible onward connections to Europe and Africa, according to the United Nations Economic and Social Commission for Asia and the Pacific.

Despite a blueprint for the three lines, surveying and construction work have been hampered due to funding difficulties and disputes over speed.

Responding to some nations' concerns on funding, China has pledged to offer financial support for the construction.

The Export-Import Bank of China has agreed to provide loans for the construction of a rail line that will link border cities in Yunnan to Laos' capital Vientiane, the Vientiane Times quoted Laotian Deputy Prime Minister Somsavat Lengsavad as saying.

He said the railway will be about 420 km long, and the cost of construction is estimated to be about $7 billion.

In China, railway planners previously set the average speed of the three lines at 200 km/h, which was later opposed by many experts who argued it would be difficult and economically unfeasible for these lines, the 21st Century Business Herald wrote, quoting an unidentified employee with China International Engineering Consulting Corp.

The speed for some sections was adjusted to 120 kmph after several rounds of discussions, the report said.

A crucial section of the eastern route, a line linking Yuxi to Mengzi - both in Yunnan - began operations in April, and the Mengzi-Hekou railway is also expected to start operating by the end of 2014, which will complete the eastern route, according to the Kunming Railway Bureau.

The survey for the central route, which runs through Yunnan, Laos, Thailand, Malaysia and Singapore, is also underway, it said.

Chinese officials said during the 10th China-ASEAN Expo, which was held in the Guangxi Zhuang autonomous region in September, that China will accelerate infrastructure projects in road and rail that connect the country and its Southeast Asian neighbors, including the Trans-Asian Railway.

"The rail lines will significantly boost the development of China's southwestern region and Southeast Asian nations," said Zhao Jian, a professor at Beijing Jiaotong University who specializes in China's rail system.

"Geographical and weather conditions in these nations are like those in China's southwestern region, so Chinese technicians and engineers should have no problem in designing and building railways there."

However, Zhao suggested that technologies used in these lines should not be too complicated due to costs and the countries' capacity to maintain sophisticated rail equipment.

"Likewise, I don't think these railways necessarily need to be high-speed lines," he said.