BEIJING — China opened the first stretch of a new high-speed railway in the western region of Xinjiang on Sunday, a milestone in the central government’s efforts to promote economic development in restive hinterlands and bind them closer to the rest of China.

The 330-mile stretch between Xinjiang’s capital, Urumqi, and Hami, a city in eastern Xinjiang, is the first stage of the 1100-mile Lanxin Railway, which will connect Urumqi to Lanzhou, the capital of the northwestern province of Gansu.

Xinhua, the official state news agency, reported Sunday that the full length of the passenger railway was on schedule to open by the end of the year.

Trains on the Urumqi-Hami leg could reach more than 120 miles per hour, more than halving the travel time between the two cities to three hours.