A major oil union in Nigeria says it will go on strike beginning Sunday if the continent's top oil-producing country does not restore a popular consumer fuel subsidy.

The Petroleum and Natural Gas Senior Staff Association said Thursday it would be forced to take “the bitter option” of shutting down oil and gas production if the government does not meet its demand.

Nigeria exports more than two million barrels of crude oil a day and a major disruption could have an impact on the country's economy and affect global oil prices.

If the oil union goes on strike, it would join two major trade unions that launched a nationwide strike on Monday, prompting tens of thousands of Nigerians to stage protests that have paralyzed major cities.

Demonstrations resumed in the commercial capital of Lagos and other cities for a fourth straight day on Thursday.

United Nations human rights chief Navi Pillay urged the government to avoid using force on protesters, saying it must “earn the respect and support” of the public by respecting human rights.

President Goodluck Jonathan and his government eliminated the fuel subsidy on January 1, causing prices to double in one day.

Mr. Jonathan said the $8 billion subsidy is no longer affordable, and he has promised to use the money instead on infrastructure and social programs.

Most Nigerians live on less than $2 a day and the fuel subsidy was one of the few benefits they received from the country's oil wealth.

Some economists have charged the subsidy was wasteful, but protesters have alleged that government corruption and mismanagement are responsible for the oil-rich nation's sustained poverty.

While Nigeria is Africa's biggest oil producer, it must import refined fuel because its own refineries do not have the infrastructure to do the job.