Four trains departed from stations in Harbin, capital of Heilongjiang; Changchun, capital of Jilin; Shenyang, capital of Liaoning; and Dalian, the port city in Liaoning, simultaneously at 9 a.m. on Saturday to mark the opening of the 921-km line.

The high-speed railway with designed speeds of up to 350 km per hour went into service after passing a two-month test during which the region saw blizzards and temperatures as low as minus 40 degrees Celsius.

"The operation of the Harbin-Dalian high-speed railway signals great progress in the building of a high-speed rail network with four lines running vertically up the country and four lines running horizontally across the country," the Xinhua new quoted Lu Chunfang, vice minister of railways.

So far, China has 8,600 km of operating high-speed railway, more than any other nation.

Sixty-seven pairs of trains will shuttle daily on the new Harbin-Dalian line.

The longest train between Harbin and Dalian on the line will take just three hours when the train runs at an average of 300 km per hour.