The Supreme Court on Monday ordered a preliminary CBI investigation into allegations that Arunachal Pradesh chief minister Pema Khandu awarded public works contracts worth Rs 1,270 crore over a decade to firms linked to his family members.

The court told the central agency to investigate the allegations and submit a report in 16 weeks.

The order came in a public interest litigation.

Advocate Prashant Bhushan, appearing for petitioner NGOs Save Mon Region Federation and Voluntary Arunachal Sena, had earlier argued that four firms connected to the chief minister's family were awarded contracts worth about Rs 1,270 crore over the last ten years, of which works worth Rs 1,245 crore were allotted through tenders and an additional Rs 25 crore was issued as direct work orders.

"There should be a CBI investigation. This is reeking of corruption," Bhushan had earlier told the bench, warning that the state police would be incapable of investigating the matter impartially.

During an earlier hearing in December, the court had described the concentration of awards as a "remarkable coincidence", observing that the negligible margin between competing bids raised concerns of possible cartelisation.

The Arunachal Pradesh government opposed the petition, with its counsel describing it as "sponsored litigation" and defending the processes followed in awarding contracts.

Khandu has denied all wrongdoing.