Gabonese oil workers warned they would start an unlimited strike on November 6, calling for restrictions on the number of foreign workers being hired in the sector.
Gabon's oil industry union ONEP threatened in a message to Prime Minister Paul Biyoghe Mba that it would call a nationwide strike, complaining about wage discrimination between foreign and Gabonese oil workers.
ONEP had warned on Saturday it would call a strike in the very near future, saying it considered that talks with the government over the issue had broken down.
It has been campaigning over the issue of foreign oil workers it said had been hired without having gone through the proper channels.
One source close to the dossier said the issue was over sub-contractors being used by oil giants Shell and Total, the two biggest oil producers in Gabon, who together account for nearly half the country's production.
Oil workers staged a four-day strike in April which, according to ONEP, cost the country 90 million euros (124 million dollars)
Gabon is fourth on the list of sub-Saharan African oil producers, with an output of between 220,000 and 240,000 barrels per day.
A statement from Oil Minister Alexandre Barro Chambrier published last week Thursday in two of the country's main newspapers said the government recognised the problem but called for the two sides to work together to find a solution.
Oil income officially accounts for 60 percent of the budget of the west African nation of some 1.5 million people.