PAGO PAGO, American Samoa — American Samoa must continue to allow Hawaiian Airlines to fly its Honolulu-Pago Pago route or else risk losing U.S. financial assistance, according to the Federal Aviation Administration.

A letter from the FAA warns Gov. Togiola Tulafono against implementing his executive order demanding Hawaiian's withdrawal in favor of another airline.

"To prevent or impede an air carrier's service at an airport is also inconsistent with the airport operator's contractual grant to provide reasonable and not unjustly discriminatory access to the airport," wrote Ronnie Simpson, manager of the FAA's Airports District Office in Honolulu in the letter dated Wednesday.

The governor has complained that the Honolulu-based airline, which has a monopoly on the key route linking American Samoa to the U.S., overcharges and subjects local citizens to discrimination and ethnic harassment.

Airline spokesman Keoni Wagner said Hawaiian will continue to fly between American Samoa and Hawai'i.

"Hawaiian is well-acquainted with the laws and regulations under which it operates, and the FAA's letter is consistent with our view of the situation," Wagner said.

The governor, in a radio address, insisted American Samoa controls its borders. Government approval is needed to clear any flights in or out of the territory.

But he was rebuffed by local lawyer Jeff Waller, who issued a legal opinion this week that had been requested by the territorial Senate. Waller said that while the governor would have the authority to set aside a foreign corporation's permit under American Samoan law, the U.S. Constitution requires the supremacy of federal law.

The opinion said the airline's authority to fly is granted by the FAA, not the territorial government.

It said federal laws and regulations are extensive and pre-empt "any state or territorial law concerning air carriers."