UPDATED: 5.21PM Six Chinese workers are dead after being hit by an express cargo train on the railway line connecting Beijing and the southern city of Guangzhou.

A local government statement about the accident said authorities are still investigating why the workers were on a live track.

State media reported in July that the number of train-related accidents and deaths had declined during the first half of 2016.

China's national safety regulator, the State Administration of Work Safety, listed one other fatal train accident this year, a crash in May that killed three people.

China has surpassed 20,000 kilometres of high-speed rail, with a target of adding another 10,000 kilometres by 2020.

The World Bank estimates China has spent $US360 billion on high- speed rail.

The rail system's worst accident on record was a July 2011 crash near the city of Wenzhou that killed 40 people and injured 191.

No other accidents of that scale are known to have occurred since then.

China's State Administration of Work Safety reported in July that far more accidents occur in China's coal mining industry, known to be one of the deadliest in the worlds, or on Chinese roads and highways.

More to come.