Eighty heavy lorries an hour will rumble past seafront homes while shingle is extracted for sea defences, latest plans reveal.

Residents living in exclusive properties at Shoreham Beach will have excavators loading the lorries close to their homes for five weeks.

The work will now go on from 8am until 6pm, five days a week rather than from 7.30am, six days a week.

Shoreham Port Authority originally wanted to take 40,000 tonnes of shingle from the west beach and use it to strengthen defences at Southwick Beach where a new concrete groyne is to be built.

But because of local concerns about the area, which is home to rare plants and a Site of Nature Conservation, the amount has now been halved.

The authority has said extraction will only take place on the "active" area of the beach to avoid disturbance to homes and to the protected plants.

It has already been granted a licence for the work by the Ministry of Agriculture, Fisheries and Food.

Government conditions which form part of the licence say measures should be taken to protect the plants and that the West Sussex Vegetative Shingle Project officer must be contacted before work starts.

A report to Adur District Council's policy and resources committee tomorrow says the work would mean eight lorries an hour going to and from the beach.

Planning officer Dereck Wade said: "The extraction is not in the form of a deep pit but spread over a wide area.

"The shingle is to be collected more by way of a shallow scraping of top material. This would be replenished naturally within 18 months."

He said that, even with the limited "one-off" extraction, the shingle levels on the sea defences for beachfront properties would not be significantly affected and would still be in excess of those required.

They would remain some of the best protected homes on the Sussex coast, he said. If the authority had to use alternate sources to provide sea defences at Southwick the council faced contributing £200,000 towards the cost.

Campaigners against the gravel extraction plans, including Shoreham Beach councillors, are expected to stage a protest before the 7pm meeting.