Apple added new rules for its global suppliers that hire workers through private employment agencies — staffing firms — the Cupertino, Calif.-based electronics company announced in a report this month.

Companies within Apple’s supply chain must ensure employment agencies they use provide legally required benefits to workers and pay them accurately and on time. Further, the employment agencies are not to charge the workers recruitment fees, and any found not to be in compliance are to be terminated.

Apple cited an instance last year in which a private employment agency was used to hire 700 foreign contract workers from the Philippines. The workers were charged recruitment fees totaling more than $1 million.

The company made its requirements public as part of its “Supplier Responsibility 2018 Program Report,” in which Apple publicizes efforts to improve its supply chain.

Apple said that in 2017, it returned $1.9 million excessive recruitment fees to 1,558 people affected by bonded labor. That brings the total to $30 million repaid to more than 35,000 employees since 2008.

Bonded labor happens when a person is forced work in exchange for the repayment of a debt, such as fees for recruitment opportunities.

In 2015, the company mandated that suppliers themselves may not charge employees any fees for recruitment opportunities even if such fees may be legal in the country in which the supplier operates.

The report looked at 31,000 employees at suppliers at 756 facilities in 30 countries.