Nigeria's oil sector is under threat of a large-scale strike over worker benefits. Union leaders say they could go ahead with the work stoppage unless two foreign managers leave the country. Workers in the Niger Delta for the Malaysian-owned oil drilling firm Wasco have already gone on strike, but now Nigeria's white-collar union, known as Pengassan, may also join in. The dispute began last year when Wasco took 50 workers off regular contracts and employed them as casual labor, depriving them of benefits. Workers also complain of racial discrimination. It escalated recently when a Pengassan representative went to the company to mediate, but instead was escorted away by police. Pengassan's secretary-general, Fada Kinte, says his union wants two foreign executives responsible in the matter to leave the country, or else a large-scale strike around the oil hub of Port Harcourt will be considered. "It's still at the branch level," he said. "The company that the workers there are on strike, they have our full backing. And if the workshop manager and the general manager stay in the country after seven days, then we shall hold a meeting at a national level and take a decision on what to do." Other officials at Pengassan say a strike could cut off over 500,000 barrels per day of Nigeria's 2.5 million-barrel daily oil output, and shut down one of the country's four refineries. The blue collar union, Nupeng, said it would also join the strike out of solidarity. Wasco was not immediately available for comment. An advisor on oil related policy, Tunde Martins, says it is in the interest of government and oil companies to eliminate the strike threat through negotiations. "Actually, the strike would not be in the interest of the oil industry in Nigeria," said Mr. Martin. "There is high expectation that the Nigerian National Petroleum Corporation will enter into dialogue with Pengassan who are the senior staff in the oil industry as to stave off any impending crisis that may lead to an escalation of oil prices on the international market." But Mr. Martins does not believe the strike would affect Nigeria's daily crude oil output, ranked among the world's top 10. Oil executives have a series of emergency measures they usually implement to continue operating during strikes, including hiring more non-contracted labor.