A production shutdown at Apple supplier Pegatron's India iPhone factory is expected to extend into Wednesday and disruptions could last longer as authorities investigate a fire at the Taiwanese firm's only India plant, four sources said.

Pegatron described the Sunday fire as a "spark incident" which caused no injuries and said has "no financial or operational impact to Pegatron Corporation", but called off all assembly shifts for Monday and Tuesday, Reuters previously reported.

Four sources briefed on the matter said Wednesday shifts were also unlikely. One of them said damage was being repaired at the plant in Chengalpattu area near the southern city of Chennai in Tamil Nadu state, and in the worst case the shutdown could last the entire week.

One of the sources said Apple representatives were collaborating with Pegatron after the incident.

Apple and Pegatron did not respond to requests for comment.

Pegatron has asked independent surveyors to assess the fire damage, a fifth source said.

The disruptions are the latest to impact Apple suppliers in India, a country where the U.S. giant is fast expanding manufacturing of iPhone and other devices for local market and exports. The affected Pegatron India plant accounts for 10% of Apple's iPhone production in the country.

(Reporting by Praveen Paramasivam, Aditya Kalra and Munsif Vengattil; Editing by Kim Coghill)