Brussels - The seizure by pirates of a Saudi Arabian oil tanker shows that NATO must step up its efforts to make the world's seas safe, the alliance's top military commander said Wednesday.

Admiral Giampaolo Di Paola, head of NATO's military committee, said there was a "growing awareness" among allies on the need to increase maritime security.

Noting that "between 80 and 90" per cent of world trade, including energy supplies, travel by sea, Di Paola said the increasing activity of pirates off the Somali coast made it even more urgent to make seas "closed to the bad guys."

NATO has deployed four warships - from Italy, Greece, Turkey and Britain - to escort food aid cargos being delivered to Africa by the World Food Programme. Another three ships are also ready to intervene.

On Saturday, pirates hijacked a Saudi Arabian supertanker, the Sirius Star, carrying some 100 million-dollars-worth of crude oil.

The seizure took place some 830 kilometres south-east of the Kenyan coastal city of Mombasa, far away from where the NATO ships are operating.

Di Paola said NATO Secretary General Jaap de Hoop Scheffer agreed that maritime security should become a "core business" of the alliance.

The admiral was speaking on the sidelines of a meeting in Brussels between NATO's top military officers.

NATO officials said discussions on the alliance's increased role in making the world's seas safer were still at an initial stage and would only be taking shape during the course of 2009. (dpa)