Those abducted were a Briton, an Italian, a Greek and four Lebanese workers, including two women, police and local government officials said.

This was the worst case of foreigners being kidnapped in the mostly-Muslim north of Africa's most populous country since an insurgency by Islamist militants intensified nearly two years ago.

No one took responsibility for the raid but northern Nigeria is plagued by attacks and kidnappings by Islamist groups. Al Qaeda-aligned group Ansaru, which rose to prominence only in recent months, claimed the kidnap in December of a French national who is still missing.

Bauchi Police Chief Mohammed Ladan said the gunmen attacked a police station and a prison overnight before storming the construction firm's compound in the town of Jama'are.

"We repelled the attack on the police station and the security men at the prison yard also repelled the attack, but they burnt two vehicles in Jama'are police station," Ladan said.

"They then attacked Setraco construction, killed a local security guard and they succeeded in kidnapping people."

Police said they were intensifying efforts to track down the kidnappers in the areas around Jama'are, a remote town around 300 miles (480 km) northeast of the capital Abuja. Setraco did not respond to requests for comment.

The Italian and Greek foreign ministries confirmed that one of their nationals was taken in the raid. Britain said it was investigating.

Islamist group Ansaru's full name is Jama'atu Ansarul Musilimina Fi Biladis Sudan, which roughly translates as "Vanguards for the Protection of Muslims in Black Africa".

It claimed responsibility for a dawn raid on a major police station in the Nigerian capital last year, where it said hundreds of prisoners were released. Last month, it attacked a convoy of Nigerian troops en route to deployment in Mali.