Two Bay Area restaurateurs have been ordered to pay $1.7 million for their treatment of dozens of former employees for garnishing the workers’ tips, denying them overtime pay and medical care, and housing them in abhorrent conditions, authorities announced Thursday.

Hai Jie Chen and Hak Chun Ng employed 56 workers in three Malaysian-Chinese restaurants around the Bay Area: Mango Garden in Fremont, Mango Jungle in San Jose and Mango Blaze in San Mateo.

For more than three years, Chen and Ng bussed their employees to and from work and required them to labor up to 12 hours a day while refusing to pay overtime, officials with the Alameda County district attorney’s office said. Many times, the workers were paid as little as $2 an hour and their tips were stolen. During this time, the owners provided dilapidated apartments for their employees, sometimes housing as many as 15 people in a two-bedroom unit with mattresses on the floor, officials said.

When Chen and Ng found out their workers were planning to sue them, they shuttered two of their companies, created new businesses and registered different owners on paperwork to avoid the lawsuit, according to the state labor commissioner’s office.

Chen and Ng’s assets were seized, and they are required to pay $1,006,455 in back wages to their workers, $550,000 in fines ordered by the labor commissioner’s office, plus more than $250,000 in employment, insurance and sales tax fraud.

“We are here to protect the rights of workers, and will bring to justice any employer who engages in exploitation of his or her employees,” District Attorney Nancy O’Malley said in a statement.

Chen was convicted of felony charges of conspiring to commit wage theft and tax and insurance fraud, while Ng was convicted of failure to pay minimum wage, a misdemeanor charge, officials said.

The district attorney’s office encourages anyone experiencing labor trafficking or labor exploitation to call the office’s worker protection division at 510-383-8600.

Ashley McBride is a San Francisco Chronicle staff writer. Email: ashley.mcbride@sfchronicle.com Twitter: @ashleynmcb