Apple Inc has placed supplier Wistron Corp on probation, saying on Saturday it would not award the Taiwanese contract manufacturer-new business until it addressed the way workers were treated at its southern India plant.

Early findings of an Apple audit in the wake of violence at the Wistron plant in India’s Karnataka state showed violations of its ‘Supplier Code of Conduct’, the Cupertino, California-based tech giant said in a statement.

Contract workers angry over unpaid wages destroyed property, gear, and iPhones on Dec 12, causing millions of dollars in losses to Wistron and forcing it to shut the plant. Apple said Wistron had failed to implement proper working hour management processes, which “led to payment delays for some workers in October and November”.

Wistron on Saturday admitted some workers at the plant in Karnataka’s Narasapura had not been paid properly or on time, and it was removing a top executive overseeing its India business. Apple said it will continue to monitor Wistron’s progress on corrective action.

“Our main objective is to make sure all the workers are treated with dignity and respect, and fully compensated promptly,” Apple said, adding that it continued to investigate issues at the plant, which is located some 50 km outside of the southern tech hub of Bengaluru and assembles one iPhone model.

“This is a new facility and we recognize that we made mistakes as we expanded,” Wistron said in a statement. “Some of the processes we put in place to manage labor agencies and payments need to be strengthened and upgraded.”