Pirates in the Gulf of Aden off the coast of Somalia have captured a Singapore-flagged cargo ship with 19 Chinese crew on board, maritime authorities said.

The Golden Blessing cargo ship is a petroleum and chemical tanker.

It was travelling to India from Saudi Arabia when it was hijacked. All 19 crew are reported to be safe.

Rescue efforts had begun according to the China Marine Rescue Centre.

Singapore maritime authorities said the ship had been chartered to Shanghai Dingheng Shipping Co Ltd, adding that they were closely monitoring the situation.

An employee of Golden Pacific International Holdings, which owns the ship, told AFP news agency that the company was in contact with the crew.

"The crew so far is safe," said the staff member, who asked not to be named.

He added that no ransom demand had been made so far.

In October 2009, a Chinese cargo ship with 25 crew members on board was captured by pirates northeast of the Seychelles as it was sailing to India from South Africa.

Last year was the most active yet for Somali pirates, with more than 200 attacks, including 68 successful hijackings and $50m paid out in ransoms, according to unofficial figures.