A Nigerian oil labour union on Friday called for the shutdown of all ExxonMobil facilities in the Niger Delta, a union representative said.
Reuters was unable to independently verify whether union members had shut down the company's facilities.
Oil sources said there had been no impact on production.
Madubuezi Azubuike, who chairs the Petroleum and Natural Gas Senior Staff Association of Nigeria (PENGASSAN) in Rivers state, said the call followed the breakdown of talks with the company over sackings and was part of a strike that began last week.
"We have called for the shutdown of all Mobil facilities across the Delta today," he said.
The industrial action is in protest at the sacking of 150 workers in December, of which 82 were PENGASSAN members.
"No resolution has been reached so far. We have had meetings with top management of the union and Mobil executives, but with no avail over issues," Azubuike said.
An ExxonMobil spokesman was not immediately available for comment to Reuters.
Strikes by ExxonMobil workers in Nigeria at the end of last year did impact output, delaying loadings by weeks.
Nigerian labour unions have held a number of strikes in the last few months over the dismissal of oil workers.