TULSA, Oklahoma - The U.S. Department of Labor has filed a lawsuit against four Tulsa-area restaurants because it says they violated the Fair Labor Standards Act's minimum wage, overtime and record-keeping provisions.

In a news release, the Labor Department says the violations resulted in a total of approximately $1 million in unpaid wages owed to 221 kitchen and wait staff, hosts and bussers at El Tequila's four restaurant locations in Tulsa, Broken Arrow and Owasso.

The suit was filed in federal court against the restaurants and owner Carlos Aguirre and seeks to recover the full amount of back wages for the employees as well as an injunction prohibiting future violations.

"The restaurant industry employs some of our country's lowest-paid, most vulnerable workers," said Secretary of Labor Hilda L. Solis. "When violations of the FLSA are discovered, the Labor Department will take appropriate action to ensure workers receive the wages they have earned and to which they are legally entitled."

The news release says the investigation determined employees, who in some cases worked as many as 72 hours in a week, were paid a fixed salary without overtime compensation for hours beyond 40 in a week.

The department also says employees did not always receive at least the federal minimum wage of $7.25 per hour.

Investigators say they also found that wait personnel were required to turn their tips over to management at the end of every shift, which caused their pay to fall below the minimum wage.

The department also says the employer did not keep proper records as required.

In a press release issued by the company Thursday, El Tequila said the allegations by the Labor Department were based on speculation.

"El Tequila is demanding its day in court. The speculation will not hold up to the light of day," the press release read.