Four service providers at US-based First Solar’s Malaysian plant broke laws in holding workers’ passports and keeping back wages, the company has acknowledged.

The company carried out audits in the US, Vietnam and Malaysia, it said. In the latter, it found foreign migrant workers had been “subjected to unethical recruitment including the payment of recruitment fees in their home countries, passport retention, and the unlawful retention of wages”.

First Solar noted that employment terms had not been communicated in native languages. Janitorial and security providers were guilty of “inadequate management system and policy”.

Some Malaysian workers had taken voluntary overtime with the result being work of more than 60 hours in a week. First Solar said it had launched a monitoring report to ensure working hours do not exceed this and that workers receive at least one day off in seven.

All passports have been returned, First Solar said, and it has updated service agreements to prevent future fees. The company has also brought in a third party to investigate and compensate workers.

The aim is to pay back fees – paid in home countries or in Malaysia – to current and recently departed workers...