British Foreign Secretary Boris Johnson has apologised to the Saudi government after an activist tried to carry out a citizen's arrest of one of the Gulf state's generals.

At least 15 people, including six children, have been killed after two vans collided in south-western Saudi Arabia.

The terror threat emanating from al Qaeda in the Arabian Peninsula (AQAP) in Yemen has focused attention on the group’s cunning leader, Nasir al Wuhayshi.