A Singaporean ship sailing from Saudi Arabia to India with 19 Chinese sailors on board was on Monday hijacked by pirates in waters of the Gulf of Aden, the China Marine Rescue Centre said.
The ship 'Golden Blessing' was hijacked by an unknown number of pirates, official Xinhua news agency reported.
Rescue effort is under way and the fate of the Chinese sailors remained unclear, it said.
China has deployed a naval task force in the Gulf of Aden to deal with the series of pirate attacks on Chinese and international ships sailing through it.
Heavily armed pirates using speed boats operate in the Gulf of Aden where they prey on ships, sometimes holding them for weeks before releasing them for large ransoms paid by governments or ship-owners.
In 2010, in one of their biggest strikes yet, Somali pirates hijacked eight Indian boats carrying 150 Indian sailors off the Kismayo coast.
In 2008, an Indian navy warship, INS Tabar destroyed a suspected Somali pirate vessel after the pirates opened fire at the ship in the Gulf of Aden.