Gunmen have kidnapped seven foreign workers from a construction company, including at least one British citizen, according to officials in northern Nigeria.

The attack happened in Bauchi state overnight on Saturday.

Police spokesman Hassan Muhammed told reporters that the attack first targeted a prison in the area.

Those kidnapped were from Britain, Italy, Greece and Lebanon, local government chairman Adamu Aliyu said.

Mr Muhammed said the attackers then went to the construction company Setraco, where they killed a guard and kidnapped the foreign workers.

Nigeria's predominantly Muslim north has been under attack by the radical Islamic sect known as Boko Haram in the last year-and-a-half. The country's weak central government has been unable to stop the group's bloody guerrilla campaign of shootings and bombings.