New Delhi -  Warships from Pakistan, China and India operated jointly in the Gulf of Aden to rescue a merchant vessel attacked by Somali pirates on Saturday night.

The Tuvalu-flagged bulk carrier was travelling from Kelang in Malaysia to the Yemeni port city of Aden when it was hijacked by the pirates, the latest in a string of attacks after several years of silence.

Immediately after receiving an SOS from the vessel, the Indian Navy diverted two of its warships - INS Mumbai and INS Tarkash - in the direction of the merchant ship.

The Indian warships contacted the captain of the merchant vessel who along with the crew had locked themselves in a strong room on board, the navy said in a press statement.

Chinese, Pakistani and Italian warships that were in the vicinity also reached the spot.

The Chinese navy sent a team of 18 men to sanitise the 178-metre merchant vessel, with the Indian Navy providing the communication link and air cover with its helicopters.

The Chinese navy’s Yulin guided missile frigate also took part in the operation.

On receiving the all-clear signal, some crew gradually emerged from the strong room and searched the ship and confirmed the pirates had fled at night, the statement said.

A boarding party from the nearby Chinese Navy ship then arrived on the merchant ship, while the Indian Naval helicopter provided air cover for the rescue operation. "It has been established that all 19 Filipino crew members are safe," the statement added.

Somali pirates began staging attacks on ships in 2005, disrupting major international shipping routes and costing the global economy billions of dollars.

At the peak of the piracy crisis in January 2011, 736 hostages and 32 boats were held.