File photo taken on Feb 14, 2015 shows a CRH2G bullet train running for a test on the Harbin-Dalian high-speed railway, Northeast China. [Photo/Xinhua]

China is to introduce "red-eye" bullet trains to cater for a growing demand, according to Chinese business publication Caixin on Wednesday.

China Railway Corp (CRC) will add "red-eye" bullet trains to its fixed operation schedule later this year, China Railway Corporation (CRC) said to Caixin. Trains running overnight are popularly known as "red-eyes".

CRC did not previously run overnight bullet trains due to safety concerns, but the company does not lack experience in running them, according to the report.

The CRC tested "red-eye" bullet trains in periods such as the Spring Festival holiday, the?report added.

Some 2.5 billion passengers took trains in 2015, up 6.07 percent from a year earlier, according to CRC statistics. The number of passengers has been on the rise for more than 10 years.

The "red-eye" trains will be equipped with sleeping cars, said a source from China Railway Rolling Stock Corp Ltd (CRRC), a railroad equipment producer.

The CRRC said the first bullet train with sleeping cars was under test at the China Academy of Railway Sciences, a research unit. The train was built by Changchun Railway Vehicles Co Ltd with a maximum speed of 250 km/h.

The?report also?said that a "red-eye" train that can run at up to 350 km/h was under test.

To meet growing demand, researchers are also developing double-decker bullet trains that could increase capacity by half.

Double-decker bullet trains are operated in France and Japan.