"Because there is no (effective) government, there is so much irregular fishing from European and Asian countries," Ahmedou Ould Abdallah told reporters.

He said he had asked several international non-governmental organizations, including Global Witness, which works to break the links between natural resource exploitation, conflict, corruption, and human rights abuses worldwide, "to trace this illegal fishing, illegal dumping of waste."

"It is a disaster off the Somali coast, a disaster (for) the Somali environment, the Somali population," he added.

Ould Abdallah said the phenomenon helps fuel the endless civil war in Somalia as the illegal fishermen are paying corrupt Somali ministers or warlords for protection or to secure fake licenses.

East African waters, particularly off Somalia, have huge numbers of commercial fish species, including the prized yellowfin tuna.

Foreign trawlers reportedly use prohibited fishing equipment, including nets with very small mesh sizes and sophisticated underwater lighting systems, to lure fish to their traps.

"I am convinced there is dumping of solid waste, chemicals and probably nuclear (waste).... There is no government (control) and there are few people with high moral ground," Ould Abdallah added.

Allegations of waste dumping off Somalia by European companies have been heard for years, according to Somalia watchers. The problem was highlighted in the wake of the 2004 Indian Ocean tsunami when broken hazardous waste containers washed up on Somali shores.

But world attention has recently focused on piracy off Somalia, which has taken epidemic proportions since the country sank into chaos after warlords ousted the late president Mohamed Siad Barre in 1991.

Piracy had come to a virtual halt under the rules of the Islamic Courts Union (ICU), who took strict measures against the pirates, but since Ethiopian troops helped oust the ICU, the phenomenon returned to Somali shores.

Somalia's coastal waters are now considered to be among the most dangerous in the world, with more than 25 ships seized by pirates there last year despite US navy patrols, according to the International Maritime Bureau.

Some Somali pirates have reportedly claimed to be acting as "coastguards" protecting their waters from illegal fishing and dumping of toxic waste.

Ould Abdallah cited the case of a Spanish trawler captured by pirates while illegally fishing for tuna off Somalia in April.

He said payment of a ransom for the release of the crew "was done in a very sophisticated manner" with the pirates arranging by phone "to be paid in Macau."

The Spanish government said in late April that it paid no ransom to secure the release of the crew of the Playa de Bakio after six days of captivity. But Andrew Mwangura of the Kenya chapter of the Seafarers Assistance Program then said a ransom of 1.2 million dollars (768,000 euros) was paid.

On Friday, Estonia urged the European Union to take stronger action against Somali pirates attacking cargo ships bound for Europe, after an Estonian sailor was held hostage for 41 days.

On Sunday pirates seized a 52,000-tonne Japanese vessel and its 21 crew members off the Somali coast.