The Wistron plant in the Narasapura industrial area of Karnataka state was shut after contract workers angry over unpaid wages destroyed property, equipment and iPhones on Dec. 12, causing millions of dollars in losses to the Taiwanese company.

Apple put Wistron on probation after its audit of the plant found violations of 'Supplier Code of Conduct'. A reopening of the plant would require Apple's approval, a fourth source said.

"Wistron reconstruction is nearing completion... and iPhone production will very likely begin next week," one of the sources said.

Wistron, which assembled the second-generation iPhone SE at the site and was expected to start making newer models, would gradually ramp up production at the factory over the next few weeks, two of the sources said.

All sources declined to be named as they are not authorised to speak to the media.

Apple did not respond to a request for comment.

Wistron, in a statement to Reuters, said it was working hard to raise standards and fix issues at the plant.

"We are looking forward to restarting our operations and welcoming back team members and we thank them for their patience and support as we worked through corrective actions," Wistron said, without giving a timeline for the re-opening of the plant.

Wistron also said it had paid all its workers and brought in new hiring and payroll systems.

"We will be delivering enhanced training programmes for all workers, and have put in a place a new system for workers to get information and raise any concerns they may have, anonymously," it added.

Apple began the assembly of its first iPhone model in India via Wistron in 2017. It has since expanded manufacturing with Foxconn in southern India and another top supplier Pegatron is set to begin operations.

(Reporting by Sankalp Phartiyal and Aftab Ahmed in New Delhi and Ben Ben Blanchard in Taipei; Additional reporting by Chandini Monnappa in Bengaluru; Editing by Christopher Cushing, Shri Navaratnam and Susan Fenton)

By Sankalp Phartiyal, Aftab Ahmed and Ben Blanchard