Watersports operators in Spain and Greece are flouting basic rules on safety, putting holidaymakers' lives at risk, the magazine Holiday Which? has warned,.

An inspector from the Royal Society for the Prevention of Accidents (RoSPA) commissioned by the magazine to carry out spot checks on 18 firms found that most were either unsafe or potentially unsafe.

Staff at the firms, 11 on the Costa Blanca and seven in Corfu, were organising parasailing and inflatable rides or hiring out jetskis. Failings ranged from the lack of a rescue boat or life jackets to a willingness to launch in unsuitable weather. Which? said that, in the absence of EU legislation, European countries had their own "inconsistent" laws on beach safety that were often enforced only after an accident.

Such a case hit the headlines last year when a British schoolboy, James Dudley, was involved in a jetski crash which killed his 16-year-old girlfriend Hannah Sutton after he illegally hired the equipment in Cyprus. The jetski supplier failed to ask for ID proving that Dudley was 18, as required by Cypriot law.At least six Britons have died in the past seven years while participating in watersports in the Mediterranean.

Of the 18 operators checked by RoSPA, seven were rated unsafe and four were potentially dangerous. Among the most worrying failing was that six operators were not wearing a "kill cord" when towing people parasailing or on inflatable rides. Safety experts recommend wearing the cords because one attached to the driver of a powerboat will stop the engine if the driver falls out of the craft, for example if hit by an unexpected wave. If no cord is worn, and the driver is incapaciated the boat can career out of control endangering the people it is towing and anyone in its path.

Holiday Which? urged people to check equipment and operating practices before participating. The editor, Lorna Cowan, said: "It's not much fun having to spend your precious holiday time in casualty. We saw too many water-sports operators who are making this all too likely with their total disregard for safety standards."