Officials hope to fill the void under the walkway at Hunstanton to make the route safe and prevent any further deterioration to the structure.

The machine is parked next to the Waterside Bar, while its long nozzle reaches over the prom to the sinkhole (Image: Chris Bishop)

The hole beneath it, which has been described as being the size of a single-decker bus, was discovered after a sinkhole appeared near the Waterside Bar on the seafront around a month ago.

Dave Robson, West Norfolk Council's environmental health manager, said two 6sqm loads of concrete had been pumped underground by lunchtime today.

Dave Robson, the council's environmental health manager (Image: Chris Bishop)

He said he did not yet know how much more concrete would be needed to plug the hole, adding: "We'll just keep going until we've filled it."

Mr Robson said it was hoped the concrete would have set in time to allow the entire prom to be reopened before the start of the Easter holidays.

A 150m stretch of the prom has been fenced off (Image: Chris Bishop)

An accelerant has been added to the mixture in the aim of speeding up the process.

A 150m stretch of prom from the Rock Shop Ramp towards the Oasis Leisure Centre is currently fenced off, forcing locals and visitors to take a detour through a car park.

The sinkhole which appeared in early February (Image: Chris Bishop)

Material has been washed out from underneath the seawall, which was built in the 1920s and back-filled with rubble.

Sheet piling is also being driven into the base of the defences to prevent further damage.

Looking down the sinkhole into the void beneath the prom (Image: West Norfolk council)

The cost of the work, which will be borne by the council, is not yet known but is expected to top £100,000.

Over the longer term work costing millions of pounds will be needed to shore up the prom after surveys showed other areas of its foundations are at risk of erosion, after changing coastal currents washed sand and shingle away from the beach.

It is hoped central government will pick up the tab via coastal defence funding.

© Eastern Daily Press