Kano - Gunmen kidnapped seven foreigners and killed a security guard when they stormed the compound of Lebanese construction company Setraco in northern Nigeria's Bauchi state early on Sunday, police said.
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 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.
The group said the abduction of the Frenchman last year was motivated by France's ban of the full-face veil and its support for military action against Islamist insurgents in Mali.
Kidnapping of foreigners for ransom has been common in Nigeria's southern oil region for years but abductions by radical Islamists in the north began only last year.
Britain in November put Ansaru on its official "terrorist group" list, saying it was aligned with al Qaeda and was behind the kidnap of a British and a Italian killed last year during a failed rescue attempt.
Ansaru is thought to have loose ties to Boko Haram, which has killed hundreds during a three-year-long insurgency focused mostly on Nigerian security forces, religious targets and politicians, rather than foreigners.
Boko Haram wants to carve out an Islamic state in a country of 160 million split roughly equally between Christians and Muslims. It poses the biggest threat to stability in Africa's top oil-producing state.
Attackers slit the throats of three North Korean doctors, killing them in their apartment in Boko Haram's northeast stronghold town of Maiduguri last week.
Gunmen on motorbikes shot dead nine health workers who were administering polio vaccinations in two separate attacks in the biggest northern city Kano this month. No group has taken responsibility for the attack.
President Goodluck Jonathan has repeatedly said that the military are winning the battle against what he calls "terrorism" in northern Nigeria.
But Western governments are increasingly concerned about Islamists in Nigeria linking up with groups outside the region, including al Qaeda's North African wing AQIM, especially given the insecurity in nearby Mali.
France intervened in Mali last month as Islamist forces, which hijacked a rebellion by ethnic Touareg MNLA separatists to seize control of the north in the confusion following a military coup in March 2012, pushed south towards the capital Bamako.
Around 4,000 French troops, backed by the Malian army and several thousand troops from other African states, including hundreds from Nigeria, have driven the Islamist alliance into the remote northeast mountains.