Nigeria has fined British Airways $135 million and Virgin Atlantic Airways $100 million for unfair trade practices that raised airfares between London and Lagos, the Nigerian capital, the Associated Press reported Thursday.

A Nigerian government official said the action followed a six-month investigation into fuel surcharges passengers have paid since 2004 on flights between the United Kingdom and Nigeria, which was a British colony before it achieved independence in 1960. The airlines will also be required to pay compensation to passengers who paid the additional charges.

Both airlines have released statements rejecting the allegations of wrongdoing. "We are vigorously defending our position," British Airways said.

The fines were announced in the midst of talks between the Nigerian airline, Arik Air and the U.K. concerning the allotment of slots at London’s Heathrow Airport. The airline is being asked to pay increased rates for some of the slots.

In the U.S., 21 airlines have paid more than $1.7 billion in fines over inflated fuel surcharges.

(Photo: MAX NASH/AFP/Getty Images)