The strike over pay and conditions comes as the threat of war in Iraq and a prolonged strike in Venezuela have pushed oil prices to a two-year high. Half of Nigerian exports go to the United States.
The action was launched by the employees of the Department of Petroleum Resources, a government unit overseeing operations of oil multinationals such ExxonMobil, ChevronTexaco, Royal Dutch/Shell and TotalFinaElf.
The strike is also backed by the country's powerful Natural Gas Senior Staff Association of Nigeria.