LAGOS, Nigeria 

Two leading petroleum workers unions in Nigeria on Tuesday said 850 oil workers have been sacked by the nation's oil corporation.

The Nigeria Union of Petroleum and Natural Gas Workers (NUPENG) and the Petroleum and Natural Gas Senior Staff Association (PENGASSAN), said in a statement on Tuesday that the nation's oil giant, the Nigerian National Petroleum Corporation (NNPC), had dismissed 850 people.

The unions said a junior minister in charge of petroleum resources recently threatened to sack some of the oil corporation staff over a labor dispute.

"It had already been carried out with the sack of 850 support staff in the midst of COVID-19 pandemic," the two unions said in the statement jointly signed by Williams Akporeha, NUPENG's national head, and Ndukaku Ohaeri, PENGASSAN's secretary-general.

The unions said the mass firing will affect thousands of families.

Oil workers in the country have been at odds with the government-owned petroleum corporation over their benefits.

Nigeria is a leading oil-producing nation in Africa and among the top 10 in the world. Petroleum exports are its major source of revenue.