British Petroleum Southwest Pacific has filed a protest regarding the American Samoa Power Authority's move to become a fuel importer and supplier.
ASPA became an importer last week after it took over Mobil's role in the territory.
BP says Mobil's action create a monopoly by giving ASPA all of its land and sea market for diesel.
It also argues that ASPA is not authorised under the law which created it to be a fuel importer and supplier.
And it says ASPA, as a quasi government agency, will be competing against private business.