One civilian was killed and a second injured in the incident which occurred at Elelenwo in Rivers State, he said.

Industry sources said the gunmen attacked the residential compound of Eleme Petrochemical.

Police in Port Harcourt, the state capital and hub of Nigeria"s multi-billion-dollar oil and gas industry confirmed the attack.

"We have a report of abduction of three foreigners at Eleme. We are still trying to get the details," a senior police officer told AFP by telephone.

He said security agents were on the trail of the attackers.

"We are worried about the rising wave of criminality, especially hostage-takings in the Niger Delta. Everything will be done to put an end to this unlawful act" he said.

No group has claimed responsibility for Saturday"s abduction, the latest to rock the restive Niger Delta in recent months.

On Monday, unidentified gunmen snatched a Nigerian working for Italian oil giant Agip in Rivers state and two days later a child and an undisclosed number of adults were seized from a vehicle and taken to an unknown location.

This month alone more than 30 foreigners have been abducted in the region. More than 150 foreign workers have been kidnapped there since the start of last year.

The vast majority have been released unharmed, but several were injured or killed by the Nigerian military in rescue attempts. Dozens of security officers have also lost their lives.

The Niger Delta area is at the centre of a long-running confrontation between the government and militants who claim to be fighting for a larger share of the country"s oil resources for local people as well as a plethora of armed gangs out to take ransom money.

The unrest has cut back Nigeria"s daily output of 2.6 million barrels by a quarter as the country"s major oil firms have substantially scaled down their operations in the volatile region.

PIN/Africasia.Com