At Okoro field off Akwa Ibom State, gunmen attacked an offshore oil rig operated by exploration firm, Afren, kidnapping five crew members, including foreigners and injuring two others.

The attack in the shallow-water field, which is Afren's biggest producing oilfield with an average output of 17,300 barrels per day, was one of the biggest of its kind since the amnesty programme took off last year.

"Two crew members are stable after receiving wounds to the leg, and have been evacuated by helicopter to a shore-based clinic. It is believed that five crew members have been taken hostage," Afren said in a statement.

A security source confirmed to Reuters that those kidnapped were believed to be two French nationals, two US citizens and one Canadian national, though there was no confirmation of this from the Nigerian security services or Afren.

The French Foreign Ministry said it had received information suggesting two French citizens were among those taken and was investigating.

Afren said the High Island VII jackup rig had recently arrived in the Okoro field and was preparing to begin drilling.

It said drilling activities were temporarily suspended. Afren shares fell as much as 9 per cent in London. The company said there had been a second security breach at a support vessel but that both the rig and the vessel were now under its control.

In an email to the media, MEND warned of more attacks.

"In the coming days, our fighters will launch a series of attacks on oil installations across the Niger Delta," it said.

It also said it was holding one Thai and three French nationals who were kidnapped several weeks ago and had since been transferred to its custody.

The three Frenchmen were kidnapped from a vessel owned by French marine services company Bourbon on September 22 by gunmen in speedboats, an attack, which was also off Akwa Ibom and similar in style to the latest strike on Afren.

The news of the planned fresh attacks came exactly two years after the group launched an all-out war tagged "Hurricane Piper Alpha" against oil companies in the region.

MEND had on November 8, 2008 announced the operation and gave oil companies operating in the region, a 72-hour ultimatum to vacate the area or face the consequence.

The latest threat, THISDAY learnt, is causing panic in the oil industry, as most companies are still counting losses following years of violence in the region, which caused them some chunks of oil production, with facilities worth billions of dollars destroyed.

Some officials of one of the oil majors told THISDAY last night that if the threat was anything to go by, then oil companies should be ready to go back to the old days of frequent production shut-in.

They noted that some companies that closed their Nigeria businesses in the wake of the heightened insecurity in the region are doing well in other neighbouring countries because the environments are conducive.

An industry expert, who expressed concern over the MEND's announcement said renewal of violence in the region would not only reduce Nigeria's crude production, which currently stands at 2.1 million barrels from an all time low below 1.2 million in 2009, but would push up production costs.

He called on the Federal Government to do everything possible to avert the attacks, pointing out that the renewal of violence in the region at a time that Nigeria plans to push for higher quota from the Organi-sation of Petroleum Exporting Countries (OPEC) to shore up its sagging economy would not be in anybody's interest.

In London, Brent North Sea crude (the equivalent of Nigeria's Bonny Light) for December, according to AFP, sold for $87.49 a barrel - the highest point since late 2008.