Asiana Airlines, a South Korean flagship carrier, was fined $500,000 Tuesday for what the U.S. aviation authorities described as negligence in assisting families of passengers aboard its jet that crash-landed in San Francisco last year.

The Department of Transportation said Asiana "violated federal law last July by failing to adhere to the assurances in its family assistance plan" following the accident in which three passengers were killed.

The federal law, set up in 1997, requires all foreign airlines to follow a "family-assistance plan" in the event of aircraft accidents.

Asiana Flight 214, carrying 307 people, struck a seawall and crashed onto the runaway at San Francisco International Airport in July.

"In the very rare event of a crash, airlines have a responsibility to provide their full support to help passengers and their families by following all the elements of their family assistance plans,"U.S. Transportation Secretary Anthony Foxx said in a news release. "The last thing families and passengers should have to worry about at such a stressful time is how to get information from their carrier."

For approximately one day following the crash, Asiana failed to widely publicize any telephone number for family members of those on board, and the only number generally available to the public that family members could call was Asiana's toll-free reservations line, the DOT said.

"In addition, Asiana took two full days to successfully contact the families of just three-quarters of the passengers," it added. "The families of several passengers were not contacted until five days following the crash."

Asiana said it acknowledges its lapses in failing to quickly notify families of passengers following the accident and some initial problems in offering assistance.

It, however, stressed it has since taken every necessary step to give extensive support to passengers and families of the ill-fated plane and will continue to do so.

"We have covered hospital, travel and lodging expenses for all those affected by the crash, and have engaged in earnest talks to reach settlement on compensation," an official for the company said in Seoul.

He said settlements have been reached in some cases, although he was not at liberty to disclose details, especially since the official investigation is still ongoing.

The National Transportation Safety Board is still investigating the exact cause of the Asiana accident. The probe is expected to finish this summer. (Yonhap News)