Residents face several nights away from home after a giant sinkhole opened up on a street in St Albans.

Twenty people were forced to leave their houses on Fontmell Close after the 66ft (20m) crater opened up across a driveway and front garden in the early hours of Thursday,

Engineers were due to start filling the 30ft (10m) deep hole with foamed concrete today - but experts are unsure how long it will take before people can return home.

Around 50 properties are still without gas, water and electricity more than 24 hours after the hazard appeared.

A spokeswoman for Hertfordshire County Council said: "At this time we cannot say exactly how long this will take, but it is likely to take several days. All agencies are working together to get residents back to their homes as soon as it is safe to do so."

While residents are waiting to be given the all-clear they can use the services of nearby Batchwood Sports Centre.

A postman was injured when a drain cover in the close collapsed on September 23, prompting Royal Mail to warn the council of the incident.

Hertfordshire County Council said the footpath was inspected but there was "no reason to suspect that the hole would collapse".

Royal Mail spokeswoman Sally Hopkins said: "Royal Mail can confirm that one of our postmen was delivering in Fontmell Close last week, when a drain cover gave way.

"We're happy to say that the postman was not seriously injured and we reported this incident to the council."

Hertfordshire County Council said: "We were informed about a hole in the footpath last week, it was inspected and barriers put around it on Wednesday 23 and work was scheduled to fill it in this morning.

"Following our inspection, there was no reason to suspect that the hole would collapse.

"Holes of this kind crop up across Hertfordshire, often for historic reasons, and we'd like to reassure the public that it is rare for them to turn into large holes."

The return to normal is likely to take weeks, the statement added.

It is the latest in a spate of sinkholes to open up across the UK in the last year.

In August a large hole reported to be 40ft deep appeared on a busy road in Manchester city centre.

Earlier in the year Traigh Golf Course, near Mallaig on Scotland's west coast, was left with £16,000 of damage after a hole appeared in part of a fairway.

In February last year another Hertfordshire garden collapsed as a 20ft-deep hole opened up in Croxley Green, near Watford.

In the same month a house in Ripon, North Yorkshire, was left close to collapse after a hole was found underneath it.