The deployment was China's first ever naval combat mission outside of its home waters.

Commenting on Monday's attack, a spokesman for China's foreign ministry said an "emergency plan" had gone into action.

Warning

"We will continue to follow developments closely and make all-out efforts to rescue the hijacked ship and personnel," he said, without elaborating on details.

The De Xin Hai was more than 1000km off the Somali coast when it was seized [Reuters]
"At the same time, the foreign ministry has also sent out a special warning to alert Chinese vessels and personnel not to go close to relevant sea areas, to avoid unforeseen circumstances."

A separate statement from the Chinese transport ministry said Beijing had asked the International Maritime Bureau to mobilise warships located near the scene of the hijacking to help in rescue efforts.

Officials said the captured Chinese ship has more than 70,000 tonnes of South African coal on board destined for India.

Equipped with fast attack boats and heavily armed, Somali pirates have recently ramped up their attacks on shipping in the region using sophisticated equipment that enables them to strike hundreds of miles offshore.

Ransom

Ships sailing through waters close to Somalia are usually warned to travel at least 1,100 nautical miles off the coast and the De Xin Hai appeared to observing that warning when it was captured.

According to shipping organisations, the pirate gangs made an estimated $30m hijacking ships for ransom last year, seizing more than 40 vessels off the Somali coast.

In February a Chinese fishing boat and its 24-member crew were freed after being held hostage for three months.