A high-speed railway line officially went into operation on Tuesday, linking cities in China's northernmost province of Heilongjiang, where the temperatures dip as low as minus 40 degrees Celsius.

The 300-km line designed to allow trains running at 250 km per hour cuts the travel time between the provincial capital of Harbin and Mudanjiang, known as "snow city," from over four hours to one hour and 28 minutes, according to the China Railway Harbin Group.

The line is China's northernmost high-speed railway. Construction of the railway started in December 2014, as one of the key projects in China's high-speed rail network scheme.

At its destination of Mudanjiang, the railway with 11 stops connects with an existing rail line between Mudanjiang and Suifenhe, which is China's major border city with Russia.

China's railway network is expected to hit 175,000 km in length by 2025, compared with 127,000 km of operating tracks by the end of last year.