BANGOR, Maine — A proposed federal rule aimed at helping U.S.-flagged cruise ships compete with foreign ships in Hawai'i could hurt the cruise ship market in Maine.

State and municipal officials and port businesses are working together to oppose a federal rule that they say would result in cruise ships spending less time in Bar Harbor and Portland and more time in ports in neighboring Canada.

Federal laws require ships flying under foreign flags to dock in another country before going to other U.S. ports. Cruise ships sailing from California to Hawai'i, for instance, typically make a token stop in Ensenada, Mexico, to meet the letter of the law.

The proposed rule change would force those ships to stay in a foreign port for at least 48 hours and allow passengers to go ashore.

Supporters say it would make Hawai'i cruises more costly for foreign-based cruise lines, bolstering U.S.-flagged ships in the Hawai'i cruise ship market.

But the net effect would also force cruise ships that come to Maine each summer and fail to spend more time in Canadian ports. That would likely force them to cut the number of port calls in Maine, said Amy Powers, director of CruiseMaine USA.

"It would drive the ships out of the U.S., and that's just bad business," Powers said.

Bar Harbor, which had more than 130,000 cruise ship passengers in 2007, and Portland, with some 50,000 passengers, would feel the effects most.

More than two-thirds of the ships visiting Bar Harbor were foreign-flagged and would be subject to the rule, Powers said.

Chris Fogg, executive director of the Bar Harbor Chamber of Commerce, said it wouldn't make economic sense for Canadian-based ships to stay in a Canadian port for 48 hours just so they could come to Bar Harbor.