Bosses of a Chinese noodle franchise failed to pay workers on 457 visas close to $650,000 over the last three years, court documents from the workplace regulator show.

Six Chinese cooks and kitchen supervisors employed at Yummy Noodle Box takeaway shops in Dubbo, Orange, Bathurst as well as Bundaberg, Queensland, between July 2010 and March last year are collectively owed $642,311.

The legal action coincides with the Fair Work Ombudsman's announcement of a national audit of 600 fast food outlets to clamp down on unscrupulous bosses underpaying staff and failing to adhere to pay documentation rules.

The regulator has taken legal action against W.X.Z. Enterprises and Xin Tai Xu and Xin Chun Xu, who both determined pay rates at the company, after employees complained.