A railway that links southwest China's Yunnan Province with the Association of Southeast Asian Nations (ASEAN) countries became operational on Saturday after seven years of construction, local railway authorities said.

The railway between Yuxi and Mengzi is part of the eastern line of the planned Pan-Asia Railway network.

The 141-km railway has a designed maximum speed of 120 km per hour. It passes through 35 tunnels and crosses 61 bridges, which together account for 54.95 percent of the eastern line's total length.

The eastern line also consists of Kunming-Yuxi Railway, which had been in operation, and the Mengzi-Hekou Railway that is under construction and scheduled to be operational end of next year.

Upon the full completion of the eastern line, it will further open up China's southwest, improve transportation and boost economic development along the line, experts said.

The Pan-Asia Railway network also consists of central and western lines and is an international railway project that will bring China closer with southeast Asia.