WASHINGTON (Reuters) -The U.S. Transportation Department said on Wednesday it will fine Mexican carrier Volaris Airlines up to $300,000 for airport tarmac delays that violate federal law.

Federal law and government regulations prohibit tarmac delays of four hours or more on international flights without providing passengers an opportunity to deplane.

The department said that in 2021 in Houston, a Volaris flight remained on the tarmac for a lengthy period without allowing passengers to deplane. A similar incident occurred in St. Louis in 2022.

Volaris will pay $150,000 of the fine and must pay the other $150,000 if it violates the tarmac rules again within a year. The department has issued similar fines in recent years.

"This enforcement action reflects our ongoing commitment to protecting consumers and holding airlines accountable," Transportation Secretary Pete Buttigieg said in a statement.

Volaris said the delays were caused by "the saturation of air terminals."

"Volaris fully complies with the laws and regulations applicable in all the countries in which it operates, prioritizing the safety of passengers and maintaining strict operational control," it said in a statement.

The department said in January 2023 that it planned to seek higher penalties from airlines and others that broke consumer protection rules, saying they were necessary to deter future violations.

In August, it fined American Airlines $4.1 million for unlawfully keeping thousands of passengers on the tarmac for hours, the largest-ever penalty for violating the rule.

American told the department the delays were the result of exceptional weather events, and that the 43 impacted flights represented less than 0.001% of the approximately 7.7 million flights operated.

In April 2023, the department imposed a $135,000 penalty on British Airways over a 2017 tarmac delay in which it failed to ensure the timely deplaning of passengers.