Tribesmen in southern Yemen have kidnapped sixteen western tourists -- twelve Britons, two Americans and two Australians.

Diplomats said they were travelling in five vehicles in the province of Abyan when they were abducted and taken to an unknown destination.

A Yemeni guide and one British tourist are reported to have escaped.

There are no further details at present.

The kidnappings come a day after tribesmen in north-eastern Yemen attacked the country's main oil pipeline, setting off a fire which is still burning.

Correspondents say Yemeni tribesmen frequently use tactics such as kidnappings and attacks on oil installations to press their demands for improved health and social services in tribal areas.

Four German tourists abducted three weeks ago are still being held in the eastern province of Marib.