London - A Dutch commando unit Saturday freed some 20 people being held by Somali pirates, the BBC has reported.

The captives were Yemeni fishermen who had been taken by the pirates following an attack on a Greek-managed tanker, the BBC said.

The captives were believed to have been on board a pirate "mother ship."

NATO spokesman Alexandre Santos Fernandes said that a Dutch warship from the NATO force in the region responded to a distress call from the tanker, and then engaged the pirate vessel and freed the captives who had been held since last Sunday. (dpa)