Federal aviation regulators have increased their oversight of United Airlines after finding violations of pilot qualification and scheduling rules, according to a published report.

The Wall Street Journal reported that a high-ranking Federal Aviation Administration official told United of the agency's concerns in a Feb. 6 letter. The letter didn't detail the violations, but the newspaper reported that they could include things like pilots flying longer than regulations allow or failing to undergo periodic checks of their skill by examiners.

In a statement to The Associated Press on Friday, United Continental Holdings Inc. said it gave FAA an outline of corrective steps. United spokeswoman Megan McCarthy said the FAA has not indicated that it could take enforcement action against the airline. The FAA can propose civil penalties if it believes that an airline has violated safety rules.

In January, top United executives sent a memo to pilots about safety concerns after recent incidents including an emergency pull-up to avoid a crash. It was not clear whether the FAA letter reported by The Wall Streeet Journal was related to the company's internal memo to pilots.