LAGOS, Nov 22: US oil major Chevron Texaco has shut down production on four offshore oil platforms in southern Nigeria amounting to 23,000 barrels of oil per day after 18 of its workers were taken hostage there this week.

Production of 23,000 bpd from Middleton, Penington, North Apoi and Funiwa (oilfields) have been shut down and personnel evacuated until the situation returns to normal, Chevron Texaco said in a statement late Friday.

Sixteen of the 18 workers taken hostage on Tuesday on board the Middleton and Penington offshore platforms, were released on Thursday following the intervention of Nigerian security forces, it said.

The Nigerian navy had said Friday that all the workers held hostages were freed while about 30 of the kidnappers arrested would be brought to Abuja for prosecution.

But Chevron Texaco said that the whereabouts of two contract employees was still unknown.

Our focus now is on trying to secure the release of the two missing workers. We continue to be gravely concerned for their safety, said Chuck Taylor, managing director of Texaco Overseas Nigeria Petroleum Co.

The company said that it was in touch with officials from the government and the Nigerian National Petroleum Corp. to ensure their safe return.

About 2,000 oil workers, including hundreds of expartriates, have either been held hostage or abducted for ransom in the past five years by gangs in the crisis-prone Niger Delta.

Although the oil firms deny paying ransoms, hostages are usually released unharmed by pirates and ethnic militants.

Oil firms operating in the region often pay local communities in the Niger Delta to provide security for their rigs, but these security teams are not armed, and the region is awash with illegal weaponry — often bought with the profits of piracy, smuggling and theft of crude oil from vandalised pipelines.

Nigeria is Africa’s largest producer of crude oil, with a daily export quota from the Opec oil cartel of more than two million bpd.

But the communities living in the Niger Delta, a swampy region about the size of Scotland dotted with oil and gas rigs and criss-crossed by pipelines, remain impoverished and angry.

Nigeria derives more than 95 per cent of its foreign exchange earnings from oil.

Protests by the oil-rich Ogoni community in southern Rivers State between 1992 and 1993 over environmental pollution and destruction of the ecosystem have forced the Anglo-Dutch oil giant to halt opeartion in the area since early 1993.

The founder and president of the Movement for the Survival of Ogoni People, Ken Saro-Wiwa, and eight of his companions in the movement were executed in November 1995 after they were convicted of the murder of four Ogoni personalities.—AFP