MOGADISHU: The Indian Navy said it has destroyed a Somali pirate 'mothership', as bandits continued launching attacks and demanded a ransom for a Saudi super-tanker seized in their most daring raid yet.

With shipping groups reporting a new surge in hijackings off Somalia, the International Maritime Bureau said pirates based in the lawless African country were now 'out of control'.

The Indian frigate INS Tabar, one of dozens of warships from several countries protecting shipping lanes in the Gulf of Aden, attacked the pirate ship late on Tuesday after coming under fire, navy spokesman Nirad Sinha said.

'The INS Tabar closed in on the mother vessel and asked her to stop for investigation,' he said. 'But on repeated calls, the vessel's threatening response was that she would blow up the naval warship' if it approached.

'The vessel...subsequently fired on the INS Tabar, and the warship retaliated in self-defence. Explosions were heard, possibly due to exploding ammunition that was stored on the vessel.'

Pirates had been on the upper deck with automatic weapons and rocket-propelled grenade launchers, he said.

Also yesterday, Kenyan police paraded eight suspected pirates in a Mombasa court, after Britain's Royal Navy captured them and killed two others in the Gulf of Aden last week, while other pirates freed a Hong Kong-flagged ship and 25 crew members seized two months ago.

But overall, the piracy crisis has grown since last Saturday's capture of Saudi super-tanker Sirius Star, with its full load of two million barrels of oil worth an estimated US$100 million (S$153 million).

Al-Jazeera television broadcast an audio tape that it said was one of the pirates making a ransom demand.

'Negotiators are located on board the ship and on land. Once they have agreed on the ransom, it will be taken in cash to the oil tanker,' said the man identified as Farah Abd Jameh.

Vela International, the owners of the ship, would not comment on the report, but Saudi Arabia's Foreign Minister confirmed that the company had begun talks.

There was no official comment on how much the pirates were demanding, but they appeared to be holding out for far more than the average ransom of between US$300,000 and US$1.5 million.

Britain's Daily Mail reported that officials involved in the release of previous ships claimed that 'electronic monitoring' showed they 'were talking' of at least US$10 million, while a Somali website put the figure at a massive US$250 million.

And since taking their biggest prize to date, the pirates have hijacked three more ships.

Mr Andrew Mwangura, from the East African Seafarers Association, said a Thai fishing boat, a Hong Kong-registered cargo ship and a Greek bulk carrier were seized on Tuesday in the gulf.

'The latest confirmation we got was the seizure of the Greek cargo ship that was taken yesterday afternoon in the Gulf of Aden,' he said.

The Greek merchant marine ministry said it had no word of a Greek-flagged or Greek-owned vessel being seized.

But Chinese officials said the Hong Kong-flagged MV Delight was seized in the Gulf of Aden. With a crew of 25, it was carrying 36,000 tonnes of wheat to Iran.

On the same day, pirates operating near the Yemen coast hijacked a Thai-operated fishing boat that was heading towards the Red Sea.

The Gulf of Aden controls access to the Suez Canal, which allows ships to go between Europe and Asia without having to take the longer and more expensive route around the southern tip of Africa. It is a crucially important route for oil tankers.

Nato, the United States and a number of European nations have all sent ships to the region to try to stop the piracy, which has increased instead.

The German navy said on Tuesday that one of its frigates had foiled attacks on two ships in the Gulf of Aden, using a helicopter to chase off pirates who fled in their speedboats.

South Korea, Japan, and Saudi Arabia are also considering sending warships to help secure the area.

The International Maritime Bureau has called on the United Nations to act over the piracy, with the head of its piracy reporting centre saying: 'The situation is already out of control.'

AGENCE FRANCE-PRESSE, REUTERS