BEIJING -- Fixed-asset investment in China's railways expanded 6.6 percent in the first quarter of this year, amid the country's efforts to build a modern railway infrastructure system, according to industry data.

Total fixed-asset railway investment came in at 113.55 billion yuan (about $16.5 billion), data from China State Railway Group Co Ltd showed.

During this period, the track-laying work for the main lines of three high-speed railways was completed, the group said, adding that breakthroughs had been made in a number of key projects under construction.

The group said it will continue to improve the accessibility and coverage of the railway network, and actively promote regional interconnection to better serve the coordinated development of the economy and society.