The world's largest oil tanker company and other maritime officials have said a more aggressive military approach is needed to tackle piracy off the coast of Somalia.

"I think that's the only solution," Martin Jensen, acting chief executive officer of Oslo-based Frontline Ltd, said on Friday.

Pirates have demanded a $25 million ransom for the Saudi Arabian-owned Sirius Star tanker which was carrying more than two million barrels of oil when it was seized in the Indian Ocean.

Jensen said Frontlien, which operates 80 oil tankers, was considering diverting its vessels away from the Gulf of Aden to avoid a similar fate befalling them. 

At least three other ships have been taken since the Sirius Star was captured last Saturday, and more than one dozen vessels with about 280 sailors on board are being held in Somali waters.

More than 120 attacks have been reported off the coast of Somalia this year.

Al Jazeera's Mohammed Adow, reporting from the Kenyan port of Mombasa, said that more Somalis were becoming involved in piracy every day because of the money that can be made from the huge ransoms paid by ship owners.

"They are being joined by former fishermen, former officials of the Somali navy and even students," he said.

'Greater support'

The International Association of Independent Tanker Owners (Intertanko) has called for international action to tackle the situation and said many operators were considering sending their vessels around the tip of South Africa to avoid pirates.