The state-run Xinhua News Agency said the country's railway minister had travelled to the area to oversee rescue operations.

Ministry officials have said investigators do not yet know what caused the collision. 

Busy network

China's rail network is the busiest in the world in terms of passenger and freight journeys and is the third largest in the world in terms of length of track.

It generally has a good safety record, although last year, at least 72 people were killed and hundreds were injured when a high-speed train jumped its tracks and slammed into another in eastern Shandong province.

The accident was the worst train crash in China since 1997, when 126 were killed in Hunan, Xinhua said.

In 2008 China's state council approved a massive $292bn investment programme to build new rail routes and upgrade the existing rail network to meet increasing demand for freight transport.