The Somali pirate "mother ship" that the Indian Navy sank in the Gulf of Aden last week was actually a Thai ship carrying fishing equipment that was being hijacked, an anti-piracy watchdog said yesterday.

"This mistaken identity may have caused the incident," said Noel Choong, head of the Kuala Lumpur-based International Maritime Bureau's anti-piracy reporting center, adding that the incident should not hamper the fight against piracy.

Choong said the ship was being taken over by armed pirates when an Indian warship fired on it. The Indian navy insisted yesterday it fired in self-defense.