SHENYANG, China, Dec 1 (Bernama) -- The world's first high-speed railway in areas with extremely low temperature, which runs through three provinces in northeastern China, started operation on Saturday as part of the country's efforts to revitalise the old industrial base, China's Xinhua news agency reported. Four trains with the initial of "G" left the stations in Harbin, capital of Heilongjiang, Changchun, capital of Jilin, Shenyang, capital of Liaoning, and Dalian, port city in Liaoning, simultaneously at 9am Saturday to mark the operation 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 had been hit by blizzards and harsh cold as low as 40 degrees Celsius below zero. "The operation of Harbin-Dalian high-speed railway signals a great progress in the building of a 'four-vertical' and 'four-horizontal' high-speed rail network," said Lu Chunfang, vice minister of the Ministry of Railways. So far, China has 8,600 kilometres of operating high-speed railways, ranking it first globally.