Five oil workers have been kidnapped in southern Nigeria's oil-rich Delta region, officials say.
A range of gangs and militant groups operate in southern Nigeria
The three Britons, one Indonesian and one Romanian were reportedly abducted near the Exxon Mobil oil company's offices in Eket town in Akwa Ibom state.
Oil workers are regularly abducted in Nigeria by gangs saying they want a bigger share of oil revenues.
The BBC's Alex Last says the line between criminal gangs and political
militants is often blurred.
Oil companies frequently strike clandestine ransom deals to free their employees, industry sources say.
According to the Reuters news agency, two Nigerian civilian security guards were killed in the latest abduction.
Earlier on Tuesday, at least five Nigerian soldiers were killed in a massive speedboat raid on a convoy of barges carrying fuel in the oil-producing Niger Delta.
Nine soldiers went missing in the raid, sources say.
Some 25 Nigerian workers for the oil firm Shell were taken hostage, but oil industry sources say they have since been released.
The Nigerian government last month pledged to crack down on armed groups in the Delta and there are indications that the military is preparing to respond to the speedboat attack.
Last month, President Olusegun Obasanjo promised strong action to curb armed groups in the Niger Delta.
Our correspondent says the incident highlights the continued vulnerability of the oil industry despite government pledges to crackdown on armed groups in the Delta.
Although there has not been a new wave of attacks on the actual oil infrastructure for some months, he says oil companies are bracing themselves for further violence in the Delta as competing politicians try to use the armed groups to secure victory in next year's elections.