Up to 600 people could be expected to visit Scylla per weekend

HMS Scylla was scuttled off Whitsand Bay in Cornwall in March to create Europe's first artificial diving reef.

But diving instructors are concerned some people do not have enough experience to dive alone on the wreck.

Those behind the scheme, including Plymouth's National Marine Aquarium, insist it poses no danger to responsible divers.

I think we've done more than was requested Juan Romero, National Marine Aquarium

Brian Allen, of the Aquanauts Dive Centre, said some divers were over-confident of their abilities and he feared too little is being done to protect inexperienced divers.

He said: "When they sank the Scylla, they left a number of sharp edges of metal when they blew some hatches. These are very easy to catch a dry-suit or BCD (buoyancy control device) on.

"Last week, one of my 12-year-olds punctured his BCD here."

The BCD, a mandatory piece of equipment for all diving which mounts on a scuba air tank, is an inflatable bladder that can be filled or emptied using an inflator mechanism.

He added that, inside the wreck, one of the main corridors was too narrow for divers to swim side by side. If there was a problem, neither diver would be able to reach the other's air supply.

Those who sunk the Scylla do not have any legal responsibility for its safety but said they did everything they could to prevent accidents.

It is estimated the wreck will bring in �1m a year in diving revenue

Juan Romero, of the National Marine Aquarium, said: "I think we've done more than was requested.

"We prepared the vessel to be safe for trained divers. We created a committee of different divers from the industry, with a range of people from commercial to sporting divers, and took all the steps necessary to provide a good site."

Scylla, decommissioned in 1993, was bought by the aquarium with �200,000 provided by the South West Regional Development Agency.

The 2,500-tonne Leander Class frigate has settled on the seabed close to the Liberty ship James Eagan Lane, torpedoed on her maiden voyage in 1944.

It is estimated that up to 600 people could visit her on any summer weekend and that it she will generate about �1m a year for the local economy.