The industry source noticed PNGIndustryNews.net's breaking story on the matter on Friday, which he "100%" agreed with.
"I heard from a few folks on the ground in PNG that Pertamina twice sent a very large due diligence team to PNG to go through InterOil's records and visit the drilling sites and LNG plant site," the industry source said.
At this stage there is no evidence that Pertamina is seeking an operating stake of the field which underpins InterOil's Gulf LNG project.
The source believed Pertamina was seeking a non-operating "measurable" stake of perhaps 10% to secure some future LNG production.
InterOil cannot legally reveal which parties have made bids, but previously it has signalled they had come from supermajors, and national oil and gas companies.
Various reports indicate that at least three supermajors have made bids for an operating stake of the Elk-Antelope field. The Gulf LNG project targets at least 3.8 million tonnes per annum but has scope for expansion.