Police cleared the area near the Cwmfelin Social Club in Manselton after a member of the public raised the alarm at 1015 GMT on Monday morning.

The immediate area surrounding the cavity has been sealed and the Indian restaurant immediately adjacent has been closed Spokesman, Swansea Council

No-one was hurt and no property was damaged.

Cars were moved as a precaution and highways officials from Swansea City Council cordoned off an area at Approach Road, Cwmbwrla.

It is thought mine workings could be to blame, but it is still unclear what has caused the cavity which is one foot in diameter.

Experts from the Coal Authority were called to the scene.

Works' legacy

"Much of south Wales is in the coalfield, and there's likely to be works dating back, in some cases, many hundreds of years," said Mike Sheldon, assistant operations manager for the south region.

He said his experts would investigate what has caused the chasm before contacting the relevant authority.

"The immediate area surrounding the cavity has been sealed and the Indian restaurant immediately adjacent has been closed," said a Swansea Council spokesman.

A spokesman for a local business, who did not want to be named, said the closure of the street had not interfered with their work.

"I believe it's not uncommon for this sort of thing to happen in this part of the world," he added.

A spokesman for the Cwmfelin Social Club was not available.