Unidentified gunmen have stormed the offices of Italian oil company Agip in Port Harcourt, southern Nigeria.
At least nine people were killed in the assault. It is reported that seven of the dead were policemen and two were civilians working at the complex.
The gunmen attacked the riverside offices on speedboats and made their escape in the same way, having stolen a large amount of money, witnesses said.
It is the latest in a string of attacks on oil companies in the Niger Delta.
According to a government official who spoke to the Reuters news agency on condition of anonymity, a group of about 30 men, wielding AK-47 assault rifles, attacked the facility by speedboat.
"There was a massive attack on the Agip offices in Port Harcourt," the official said.
After a lengthy gunfight with police, the assailants robbed a bank on the premises and safely made good their escape, without losing any members of their group.
Local resident Damka Pueba arrived at the scene shortly after the shooting stopped.
She described scenes of chaos to the BBC news website. Staff were fleeing the building as local police ran inside and hundreds of anxious relatives gathered in hope of news about their loved ones.
"A crowd of about 800 people had gathered at the scene. Many of them were crying," she said.
A spokesman for Agip confirmed that there had been an "incident" at the complex, but gave no further details.
The oil company's headquarters in Port Harcourt are in a complex of buildings called the Agip Industrial Area, in the Mgboshimini area of the city.
It comprises a large complex of offices, workshops and jetties run by the company.
Eni, the Italian energy giant which owns Agip, has been operating in Nigeria since 1962.
Locals complain they do not get an adequate share of the profits
In 2004, Eni accounted for approximately 10% of oil and gas production in Nigeria.
It is unclear if robbery was the sole motive for this latest attack. It comes just days after militants who have kidnapped four foreign oil workers and attacked a Shell oil platform said they were preparing to carry out more raids.
The rebel group, the Movement for the Emancipation of the Niger Delta, says it wants a share of the Niger Delta region's enormous oil wealth, and is demanding the release of two local Ijaw leaders.
The foreign hostages have been captive for more than two weeks and kidnappers say one of the men, an American, is very ill.
Oil workers' unions in Nigeria have threatened to withdraw members from the main oil-producing region unless the government moves to improve security.
The instability has led to a 10% fall in Nigeria's oil production. The country is Africa's leading oil exporter and the fifth-biggest source of US oil imports, but despite its wealth, many Nigerians live in abject poverty.
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