China has rescued a group of 26 fishermen, mainly Chinese and Vietnamese, who were taken from a Taiwanese trawler and had been held by Somali pirates for the last 18 months, the Chinese government has said.

The fishermen, who worked on the Taiwanese trawler "FV Shiuh Fu No 1", were seized in December 2010, the Chinese foreign ministry said in a statement on its website (www.mfa.gov.cn) late on Tuesday.

It gave no details about how the rescue was accomplished. The crew consisted of 13 mainland Chinese, 12 Vietnamese and one Taiwanese, it said, Reuters reports.

"After the hard work of many sides, the whole crew of 26 people was safely rescued on the evening of July 17, Beijing time," the brief statement said.

Taiwan's foreign ministry said it had assisted in ransom talks between the boat's owner and the pirates, although it did not say directly whether a ransom had been paid. It also thanked China for its assistance in the rescue.

Chinese naval forces operating on anti-piracy patrols in the Gulf of Aden and waters off Somalia were looking after the fishermen and were taking them to Tanzania, after which they would be sent home, the Chinese statement said.

Chinese ships have undertaken anti-piracy operations off Somalia since late 2008. In early 2010, Beijing agreed to join a multi-nation effort to protect shipping in the Gulf of Aden and nearby stretches of the Indian Ocean.

Somali pirate gangs can stay out at sea for long periods using captured merchant vessels as mother ships and have been using Yemen's remote island of Socotra as a refuelling hub.

The Somali piracy crisis is costing world trade billions of dollars a year.