The pirate “mothership” destroyed by the Indian Navy in the Gulf of Aden was a Thai fishing boat that had been hijacked and whose crew were tied up below decks.

The vessel, which was sunk by INS Tabar, an Indian frigate, on the night of November 18, was the Ekawat Nava 5, a deep-sea trawler, rather than a floating pirate armoury loaded with supplies of ammunition and explosives, as India had claimed.

Wicharn Sirichaiekawat, the manager of the Bangkok-based Sirichai Fisheries, the ship’s owner, said that the facts emerged when one of his crew was found alive, adrift in the Indian Ocean. He said that 14 others were still missing and at least one was confirmed dead. The new development was confirmed by the International Maritime Bureau (IMB).

The news is an embarrassment for India’s Navy, which had been praised for taking the fight to the heavily armed Somali pirates that are terrorising the Suez Canal trade route.

The incident is likely to prompt a review of the terms of engagement by the maritime forces patrolling the Indian Ocean, which include the Royal Navy, security analysts said.

Somali gangs have attacked 96 ships this year, seized nearly 40 and currently hold 15, including a Saudi supertanker carrying oil worth $100 million (£65 million), according to the IMB. More than 300 crew members are being held hostage and millions of dollars in ransoms have been paid.

Yesterday the Indian Navy insisted that INS Tabar had acted in self-defence after being threatened. Earlier it had released photographs of the incident, which showed a large explosion on board the targeted vessel. Disputing that account, Mr Wicharn said the trawler was heading to Yemen from Oman to deliver fishing equipment when it was attacked by two pirate speedboats. The pirates were in the process of boarding the fishing vessel when the Indian Navy appeared, he added.

An Indian Navy spokesman told The Times: “If it is their vessel, you will have to ask them why they are only making these claims now.”

When it was pointed out that the story had emerged only after the rescue of the crew member after nearly a week adrift, he said: “Why then have they not filed a complaint with the UN or some other official body? We have received no complaint from the Thai Government.”

Details of the two-hour stand-off between the two vessels remain scant. India has said its ship was threatened by pirates but has not made clear if radio contact was made between the vessels. The navy spokesman said the INS Tabar did not ask the pirates if they were holding hostages. The Navy refused to respond to The Times’s request for clarification of events.

The IMB said the Indian Navy ship may not have received a bulletin explaining that the Thai ship was being hijacked.

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