The Federal Government of Nigeria has ordered some foreign oil and gas companies to pay nearly $20 billion in taxes owed to states, industries and government.

A letter sent to the affected companies earlier this year via a debt collection arm of the government, Nigerian National Petroleum Corporation (NNPC) cited what it called outstanding royalties and taxes for oil and gas production.

Specifically, Royal Dutch Shell, Chevron, Exxon Mobil, Eni, Total and Equinor were each asked to pay the federal government between $2.5 billion and $5 billion.

Confirming the development, Equinor which produced around 45,000 barrels per day (bpd) of oil in Nigeria in 2017, said other operators in the oil and gas industry have also received similar requests.

“Several operators have received similar claims in a case between the authorities in Nigeria and local authorities in parts of the country,” an Equinor spokesman said.

The charge is coming after the Federal Government and states settled a dispute over the distribution of revenue from hydrocarbon production. The sides had agreed that Abuja would pay the states several billion dollars.

The tax demand adds a fresh challenge to energy companies investing in Nigeria, which have been negotiating production-sharing agreements with the government to develop and operate giant offshore fields.