One person is dead, 19 are in hospital and 18 others are missing after a subway tunnel under construction collapsed in eastern China Saturday, according to official state media reports.

A 20-metre-wide section of road over the construction site gave way, according to one local official, leaving behind a crater into which more than 11 vehicles fell.

More than five metres of water from a nearby river seeped into the open pit and subway tunnel. Five scuba divers were searching for survivors, the official state Xinhua News Agency reported.

Witnesses said that more than 25 people who had been riding a bus that fell into the crater escaped.

About 2,000 rescuers frantically pumped water out of the tunnel, searching for as many as 16 construction workers who were believed to be still trapped in the rubble, Xinhua reported.

The total number of trapped people is unknown but witnesses told Xinhua that more than 50 people were still underground.

The nearly 70-kilometre subway project, which is being built in the eastern city of Hangzhou, is scheduled to be completed in 2011.

With files from The Associated Press