May 2 (Bloomberg) -- Exxon Mobil Corp. said its Nigerian oil unit started producing after the company and an oil workers union ended an eight day strike yesterday.

``We have started production,'' Gloria Essien-Danner, a spokeswoman for Exxon's Nigeria unit, said in a telephone interview today. Essien-Danner said the company would be issuing a statement with further details.

A branch of the Petroleum & Natural Gas Senior Staff Association of Nigeria, or Pengassan, began the strike on April 24 after to failing to reach an agreement over pay. The industrial action halted about 860,000 barrels of crude a day, Pengassan branch chairman Olusola George-Olumoroti said.

The strike, along with separate militant attacks on pipelines run by other companies had crippled about half of Nigeria's oil output, boosting prices.

Levi Ajuonuma, a spokesman for the Nigerian National Peroleum Corp., which helped mediate the negotiations, said it would take 4 to 5 days for production to be fully restored.

The strike, combined with a series of militant attacks against crude pipelines operated by a Royal Dutch Shell Plc unit, had allowed Angola to overtake Nigeria as Africa's biggest oil producer. The disruptions also helped boost oil futures prices to a record $119.93 barrel in New York on April 28.

Shell Chief Financial Officer Peter Voser said on April 29 that Shell's Nigerian joint venture was losing 169,000 barrels of production a day because of recent militant attacks.

In March, Nigeria pumped 1.96 million barrels of crude a day and Angola 1.93 million barrels a day, according to Bloomberg estimates.

To contact the reporter on this story: Julie Ziegler in Lagos at jziegler@bloomberg.net

Last Updated: May 2, 2008 07:51 EDT