June 20 (Bloomberg) -- Workers at Chevron Corp.'s Nigerian unit plan to strike on June 23 after talks with management failed to resolve a labor dispute, a union official said.

Production is unlikely to be affected on the first day as a skeleton staff remains in place, Jonathan Omare, secretary of the local Chevron unit of the Petroleum and Natural Gas Senior Staff Association of Nigeria, said. Output may be affected o the second and third day of the strike should the union decide to escalate action, he said.

``Yesterday talks broke down,'' he said in a telephone interview. ``We shall begin disruption of some level of operations from Monday and it will be graduated'' upward during the rest of week.

The union has demanded the removal of Fred Nelson, head of the Nigerian unit, in a letter sent to Chevron executives in California. The union alleges safety standards have lapsed and Nigerian employees have been replaced with expatriates. Chevron in 2007 produced about 350,000 barrels of oil a day from its 32 fields in Nigeria, the company's Web site said.

Lumumba Okugbawa, the union's deputy general secretary, confirmed the plan for a partial strike, adding that other options may be considered if state-owned Nigerian National Petroleum Corp., a partner in Chevron's joint venture, intervenes in the dispute.

A meeting planned for today with the head of NNPC had to be delayed until next week, Omare said.

Brent Premium

The threat of further disruptions in Africa's second- largest producer has helped push Brent's premium over New York crude to 45 cents, its highest since Feb. 6. West African exports are priced using Brent.

Brent crude oil for August settlement gained as much as $2.95, or 2.2 percent, to $134.95 a barrel on London's ICE Futures Europe exchange today. It was at $134.44 at 1:19 p.m. London time.

Margaret Cooper, a spokeswoman for Chevron, didn't immediately respond to an e-mail seeking comment.

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

Last Updated: June 20, 2008 08:27 EDT