At least 21 railway workers have been killed in northwest China after a vehicle transporting them to work overturned, state media reported.

Xinhua news agency said the accident occurred when the workers were en route to a construction site in Gansu province's Lintao county.They were working at a site on the Lanzhou-Chongqing line.

This is the third rail-related accident this year in China. A high-speed accident involving two bullet trains near the eastern city of Wenzhou in July killed 40 and left nearly 200 others injured. In September a metro collision in Shanghai caused nearly 300 injuries. The railways ministry had ordered a halt to ongoing rail projects earlier this month.

In February, Liu Zhijun, the railway minister behind the building of the nation's high-speed rail system, was fired as an investigation into charges of graft began.