An Indian warship destroyed a pirate "mother vessel" in the Gulf of Aden, the navy said Wednesday, as bandits demanded a ransom for a Saudi super-tanker seized in the most daring sea raid yet. (UPDATED)

The Indian frigate INS Tabar, one of dozens of warships from several countries protecting shipping lanes in the area, attacked the Somali pirate ship late Tuesday after coming under fire, navy spokesman Nirad Sinha was quoted by AFP as saying.

The incident came as shipping groups reported a new surge in hijackings off Somalia and the International Maritime Bureau said pirates based in the lawless African nation were now "out of control".

"The INS Tabar closed in on the mother vessel and asked her to stop for investigation," the New Delhi navy spokesman said.

"But on repeated calls, the vessels threatening response was that she would blow up the naval warship" if it approached," he added.

An exchange of fire ensued, causing explosions and the Indian navy ships then used heavy guns.

The piracy crisis has grown since the capture of Saudi super-tanker the Sirius Star on Saturday. The huge vessel was carrying a full load of two million barrels of oil worth an estimated 100 million dollars.

Al-Jazeera, the Arabic satellite television channel, 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, who did not indicate the amount to be paid.

"We assure the safety of the ship that carries the ransom. We will mechanically count the money and we have machines that can detect fake money," the man said on an audio tape produced by the Arab television network.

Vela International, owners of the ship, refused to comment on the report. "We hope there will be a quick solution," a spokesman in Dubai told AFP.

Somali pirates have seized another ship, a Greek bulk carrier, despite a large international naval presence in the waters off their lawless country, a regional maritime group said on Wednesday.

The vessel was the second they have taken since the weekend's spectacular capture of the Saudi supertanker.

It was the latest attack in a wave of Somali piracy this year that has driven up insurance costs, made some shipping companies change their routes and prompted an unprecedented military response from NATO, the European Union and others.

"The pirates are sending out a message to the world that 'we can do what we want, we can think the unthinkable, do the unexpected'," Andrew Mwangura, coordinator of the East African Seafarers' Assistance Programme, told Reuters in Mombasa.

His group said the Greek ship was taken on Tuesday in the Gulf of Aden with between 23 and 25 crew on board. This followed the hijacking of a Hong Kong-flagged ship carrying grain and bound for Iran.

An explosion in piracy this year off the poor and chaotic Horn of Africa nation has been fuelled by a growing Islamist insurgency onshore -- gun battles broke out again in Mogadishu on Wednesday -- and the lure of multi-million-dollar ransoms.

The Saudi supertanker Sirius Star was seized on Saturday after dodging international naval patrols in their boldest strike yet.

A spokesman for the owners, Saudi Aramco, said the company hoped to hear from the hijackers later on Wednesday. One Somali website said the attackers were demanding $250 million.

The Sirius Star was seized 450 miles southeast of Mombasa, far beyond the gangs' usual area of operations. On Wednesday, it was believed to be anchored near Eyl, a former Somali fishing village that is now a well-defended pirate base.

"Eyl residents told me they could see the lights of a big ship far out at sea that seems to be the tanker," Aweys Ali, chairman of Somalia's Galkayo region, told Reuters by telephone.

The Sirius held as much as 2 million barrels of oil, more than a quarter of Saudi Arabia's daily exports, and had been heading for the United States via the Cape of Good Hope.

More of the world's big shipping firms are quietly diverting their fleets via the Cape of Good Hope, experts say, but there is little evidence that big oil tanker firms carrying most of the world's crude are avoiding Suez, though many are expressing deep disquiet about Somali pirate activity.

Somali gunmen are believed to be holding about a dozen ships in the area and more than 200 hostages. Among the vessels is a Ukrainian ship carrying 33 tanks and other weapons that was captured in another high-profile strike earlier this year.

The Sirius Star was seized despite an international naval effort, including by NATO, to guard one of the world's busiest shipping routes. Warships from the United States, France and Russia are stationed off Somalia.

Given that the pirates are well armed with grenades, heavy machineguns and rocket-launchers, foreign navies have been steering clear of direct confrontation, and in most cases the owners of the hijacked ships are trying to negotiate ransoms.

British Royal Navy Commodore Keith Winstanley, deputy commander of the Combined Maritime Forces in the Middle East, said coalition forces could not be everywhere.

"The pirates will go somewhere we are not," he told Fairplay, part of defense analysts Jane's Information Group. "If we patrol the Gulf of Aden then they will go to Mogadishu. If we go to Mogadishu, they will go to the Gulf of Aden."

In a show of resolve, Kenyan police paraded eight suspected pirates in a Mombasa court on Wednesday. The Royal Navy captured them, and killed two others, in the Gulf of Aden last week.