The move is part of crack down designed to increase the quality of diving on offer and ensure that safety standards are in place for dive tourists visiting Malta, specialised website Divernet reported.

"There are probably about twenty unlicensed dive centres currently operating," a spokesperson for Maltaqua was reported to have told Divernet "We expect that the seven served with notices will now be trying to comply with the regulations and apply for a licence, but we would be surprised if they are successful."

New legislation came into force in May of this year which handed the regulation of dive centres to the Maltese Tourist Authority. The MTA acted after receiving a number of complaints from established, licensed dive centres about the number of temporary, unlicensed dive centres which were being opened just for the peak summer season before disappearing.

The website said divers are advised to check whether the centre they are using is licensed before booking diving - a full list of licensed dive operators is available on the Maltese Tourist Authority website.