The high-speed trains from Harbin to Dalian in Northeast China will switch to the summer schedule starting on April 21, and trains will run at 300 km per hour, up from 200 km per hour, China Railway Corp said on Friday.

The traveling time from Harbin to Dalian will be cut to three hours and 30 minutes, down from five hours and 40 minutes in the winter. Ticket prices will also increase.

The 921-km rail line is the world's first ever high-speed rail running through regions with extremely low winter temperatures.

The route adopts different operation speeds in summer and winter. Train speeds are slowed during winter due to safety concerns.

Since it started operations on Dec 1, 2012, the line has made more than 8.58 million passenger trips by March 20, the company said.