Dive centre owners are appealing to the authorities to outlaw fishing over popular wreck sites after divers have reported encountering nets which put them in danger.

Only last Sunday morning, a boat stopped over the scuttled tugboat Rozi at Cirkewwa and dropped a net over the front section of the vessel while a substantial number of local and foreign divers were using the area.

Tonio Falzon, who runs a dive centre in St Paul's Bay, said: "The boat that was in Cirkewwa is obviously not licensed and it is illegal to be so close to shore in any case. There were divers on the Rozi at that time and they risked getting caught up in the net. It's about time something was done."

Mr Falzon said the Rozi was a fertile breeding ground for fish. Which is probably why the net was dropped by the boat, during the night, before eventually being lifted out of the water at around 9 a.m.

Another diving instructor, Alex Buttigieg, told The Times: "We are encountering several nets a week on various wrecks and this is especially dangerous on night dives when a diver may not notice a net till he's trapped in one. Apart from that, visiting divers are shocked that fishing is carried out at popular dive sites and it is a bad advert for Malta."

Wrecks are a rich source of marine life in the sea surrounding Malta that is otherwise largely deprived of the wildlife that can be seen at other dive destinations.

However, surprisingly, draping a net over one of Malta's dive attractions is not illegal if the wreck is within the legal fishing distance away from the coast.

Tonio Anastasi, who runs a dive centre in Sliema, believes the authorities must legislate to ensure there is a no fishing zone around popular wrecks.

"We have gone to the trouble and expense of creating wrecks to attract divers to our shores - which has been an incredibly successful initiative - but then allow people to fish there.

It is undoing all the good work."

Mr Anastasi said fishermen and divers would also benefit if zones in the sea were identified and monitored to ensure no fishing was carried out for certain periods.

"This would allow fish to breed, grow, and increase in population terms. When Filfla was a no fishing zone, there were hundreds and hundreds of fish. Yet look at it and places like it today. If bigger countries can monitor what's happening in their waters, then so can we.

"Apart from that, it's a known fact that once a wreck is full of fish, the populations will branch out to other areas. This will do everyone good."

The three instructors pointed out that as well as curbing certain fishing practices, the authorities should also ban scuba divers carrying spear guns.

"Speargun fishermen are coming to sites with lots of foreign divers. This is not only dangerous but is giving Malta a bad name. Then the tourists go home and complain that our sea has a lack of fish."