The owner of three Boston restaurants, including Sunset Grill & Tap, has agreed to pay 70 workers $675,000 in back wages and damages for violating federal labor laws, according to the US Department of Labor.

The federal agency said that an investigation it launched into wage practices at Sunset Grill & Tap, Sunset Cantina, and Big City Restaurant found the establishments — which are all owned by Marc Kadish — did not pay employees overtime for weeks when they worked more than 40 hours, and did not combine hours for employees who logged more than 40 hours in a week by working at two of the company’s locations.


Kadish, who could not be reached for comment Monday, also failed to record cash payments made to employees whose wages were paid by both check and cash, and did not maintain accurate daily and weekly records of hours worked, according to the labor department.

The investigation covered May 2009 to August 2011, and January to May of this year. The deal calls for the employees to receive $337,500 in back wages, as well as $337,500 in damages.

“This settlement reflects the department’s determination to ensure that workers receive the full amount they’re entitled to under the law — including liquidated damages where the facts justify that result,’’ said Michael D. Felson, regional solicitor for the labor department. The damages were paid on July 15 and the back wages are due by Oct. 15, the government said.

“We are putting the industry on notice that violations will not be tolerated,’’ George A. Rioux, director of the federal agency’s Boston District Office, said in a statement. “Such behavior not only denies workers their hard-earned wages, it also places other employers who comply with the law at a competitive disadvantage.’’