Between 100,000 and 150,000 tonnes of oil sludge, chemical residues and other noxious substances are illegally discharged into the Mediterranean Sea from ships every year.

"Using satellite images, the European Commission's Joint Research Centre monitored 1,683 voluntary spills from ships into the Mediterranean Sea in 1999. In 2000, the number of spills went up to 2,350. It is estimated that the spills will continue to increase unless something is done," Roberto Patruno, director of the Malta-based Regional Marine Pollution Emergency Response Centre for the Mediterranean Sea (Rempec). told The Times.

A regional centre assisting Mediterranean countries in combating oil pollution, Rempec was established in 1976 following the Barcelona convention when 16 Mediterranean countries and the European Union endorsed an emergency protocol concerning cooperation in combating sea pollution by oil and other hazardous substances. Rempec helps states strengthen their facilities to combat a major marine pollution accident and to provide a framework for exchange of information.

"As a result of international law, the Mediterranean Sea is a protected area where no substance can be released, yet voluntary spills of substances occur, especially in international waters where it is difficult to enforce or prosecute shipping companies for their actions," Mr Patruno said.

A major route for crude oil transportation, the Mediterranean Sea is already considered to be a vulnerable region. It is estimated, in fact, that 90 per cent of all oil tanker traffic from the Suez Canal and from the Sidi Kerir pipeline terminal in Egypt headed to Gibraltar passes between Sicily and Malta, then following the coasts of Tunisia, Algeria and Morocco. Accidental spills of oil and hazardous chemicals through accidents, though potentially devastating, "are not the only cause for concern".

Mr Patruno explained that spills also took place through "operational" pollution involving the release of hazardous substances out at sea.

"Hazardous substances end up in the sea during bunkering and even when tanks are washed from sludge and residues. Some substances are even more harmful to the environment than oil," he said.

Mr Patruno said prosecuting the crew and the shipping companies for such a crime is very difficult since spills occur in international waters where countries have no jurisdiction and therefore cannot intervene.

"The main obstacle is that reports on these spills have to go via diplomatic channels to the flag state of the ships which often care very little about these incidents. But by agreement, the jurisdiction of the coastal state can be extended into international waters only for this purpose," he said.

Mr Patruno pointed out that France was the only country to have adopted this policy since the beginning of this year. "Three vessels were caught discharging illegal substances into the sea. They were heavily fined and their vessels were detained for a number of days."

Mr Patruno said Rempec is trying to convince the other Mediterranean countries to adopt such a policy.

With the financial support of the European Union, Rempec will conduct a study to evaluate the present status of reception facilities in the Mediterranean ports and to propose measures ensuring that these facilities are available.

"Unless you make sure that ships have adequate facilities where to discharge their waste, you cannot expect to enforce laws effectively," he said.