Federal officials are also investigating claims made by Mainline Airways on its Web site that it will begin flights in July for a Los Angeles-Honolulu route, at a time when major airlines are charging premium summer rates.

Mainline is not certified by either Hawai'i or Federal Aviation Administration officials to fly. And under federal regulations, "no one can advertise to offer airline services unless they are authorized by the FAA to act as an airline," said FAA spokesman Donn Walker. "It's real simple."

State officials with the Office of Consumer Protection obtained the restraining order against Mainline on Friday to prohibit the company from selling tickets or collecting money before it complies with federal and state laws.

The restraining order is good for 10 days. State officials then will seek a preliminary injunction at a June 16 hearing before Circuit Court Judge Eden Elizabeth Hifo, said Stephen Levins, an attorney with the Office of Consumer Protection.

"Basically this airline, or whatever it calls itself, has not even begun to meet the requirements to operate as an airline under the FAA rules and regulations and also has not met any of the state requirements," Levins said. Even if the company plans to operate as a charter, Levins said, it still has not complied with state and federal requirements.

State officials believe that hundreds of Hawai'i and Mainland customers may have bought tickets with Mainline, "but we don't know for sure," Levins said.

The Office of Consumer Protection is interested in talking to anyone who may have purchased Mainline tickets; they may call 586-2653, Levins said.

"The investigation wasn't going to be dictated by the breadth of the harm," Levins said. "The fact that even one or two consumers paid money to someone who wasn't supposed to take it was enough to seek the temporary restraining order. ... We don't want any more people in Hawai'i or around the country to be giving over their money to someone who has not taken the necessary steps to operate."

State officials initially believed Mainline was run by Luke R. Thompson out of Massachusetts. They now believe Thompson is in Pennsylvania.

Thompson did not respond to an e-mail request today for an interview.

Mainline has been offering fares as low as $89 for one-way flights from Honolulu to Los Angeles while other airlines are making round-trip Los Angeles flights for as much as $1,000.

Mainline said its price is good until May 2004, according to the company's Web site.

On that site, Mainline advertises Boeing MD-10s refitted with leather chairs and personal televisions for every seat.

"Mainline Airways is not an airline," Walker said. "It's a web site. That is the fact on the ground as of today."