A main road in central Watford has been closed after a sinkhole has opened up underneath it.

Hertfordshire County Council has shut off St Johns Road, between Woodford Road and Clarendon Road, this morning to carry out an investigation.

The authority said the closure could be in place for four days or more.

An initial investigation started last week after severe cracking was road by the junction by Clarendon Road.

However these were stopped after investigators became concerned about undermining the road and footway any further. 

A geotechnical engineer, who was present during the investigations said it is possible that there is a sink hole deep down in the underlying chalk.

Today council workmen are due to start further investigations to excavate a hole from the footway to the middle of the road. 

This will require the road being closed for all traffic.