A reef built by worms and a ridge of sandbanks off North Norfolk could become no-go areas for sea users under a new wave of conservation measures.But any conservation clampdown would not have any major impact on the local fishing industry the government assured yesterday.

A reef built by worms and a ridge of sandbanks off North Norfolk could become no-go areas for sea users under a new wave of conservation measures.

But any conservation clampdown would not have any major impact on the local fishing industry the government said yesterday.

Plans are due to be announced next week for seven areas off the UK shores to be turned into marine parks, under new conservation powers.

What is being hailed as the biggest change to marine law in a century is aimed to protecting important habitats such as cold water corals, and species including dolphins.

One spot earmarked for a possible offshore Special Area of Conservation are the North Norfolk sandbanks around 30km offshore.

They are the best and biggest examples of offshore tidal sandbanks in UK waters. And it is also home to a reef made by tube-building ross worms - one of only four of its kind in the UK.

Under the new SAC powers there could be a ban on commercial fishing, and "extractive activities" such as oil and gas wells.

But Defra officials say there will also be shades of grey, with some areas getting a lighter touch level of controls, to allow activities to continue providing they were not harming what was being protected.

"We want to protect habitats, but we also want a sustainable fishing industry - so it is about striking a balance," said a spokesman.

The worm-built reef was about the size of a football pitch, though it had been bigger, said a spokesman for the government's joint nature conservation committee advisory body, which was tasked with identifying possible offshore SAC sites.

The sandbanks were home to clams, worms and some crabs, though crustaceans preferred rockier areas.

The sites were a long way offshore with a limited amount of activity so any protection was unlikely to have a major impact, including on fishermen.

A major consultation towards the end of the year would enable people to challenge the plans.

There are already SACs operating inside the 12-mile inshore waters limit including the Wash and north Norfolk coast. The new powers, part of the European Habitats Directive, would tackle areas from 12 to 200 miles offshore.

Tim Venes, manager of the North Norfolk Coast Partnership, said there would be fears about the area being closed off, but in his experience habitat protection did take into account the needs of the local economy too, and was "not a threat."

Other areas earmarked include the Dogger Bank, Lundy Island in the Bristol Channel and the Darwin Mounds coral reef off north west Scotland where trawling has already been banned under emergency measures.

Mr Venes added that even in areas like Lundy where there had been a total ban on fishing, it created nurseries which fed stocks to the surrounding areas.

North Norfolk MP Norman Lamb welcomed any conservation moves but said they had to be balanced with the needs of the fishing industry, and called for consultation to be through and listened to.

He would be writing to the ministry to seek clarification on the local implications of the new measures and possible sites.