Construction of a 12.3-kilometer railway tunnel linking Dali and Lincang in Yunnan province completed on Tuesday, according to the railway's project department with China Railway 12th Bureau Group Co Ltd.

It marks the country's first tunnel longer than 10,000 meters in the longitudinal valley zone of the Hengduan Mountain range in southwestern China, the department said.

Named Xinhua Tunnel, it sits in Nanjian county of Dali Bai autonomous prefecture and passes through a connecting part of Wuliang Mountain and Ailao Mountain featuring complicated geological formations.

During the past four years, the construction workers have dealt with various difficulties for this tunnel, including high seismic intensity as well as high geothermal and high hydraulic pressure, said Zhao Fan, a manager of the project department.

The successful construction of the tunnel will provide rich experience and technical guidance for the following construction of railways linking Sichuan province and Tibet autonomous region, as well as those linking Yunnan and Tibet, Zhao said.

The Dali-Lincang railway, with a length of 202 kilometers, is a key part of the international rail line linking China and Myanmar. It will require only three hours by train from Kunming, the capital city of Yunnan, to Lincang, after the railway is put into operation.