InterOil and PNG LNG project operator ExxonMobil remain in exclusive negotiations, which unless extended, can continue up to late July.
"As a country there is some concern that it may not be a wise thing to allow one major energy company to dominate the industry in the country," Duma said, according to Radio New Zealand.
"There has already been some concerns expressed by some influential sections of the community so we are also mindful of that."
Duma has long been supportive of Royal Dutch Shell, which is widely considered to be one of the competing bidders for a slice of InterOil'sElk-Antelope fields in Gulf province.
Exxon aims to use Elk-Antelope gas to underpin at least a third train expansion of the PNG LNG project.
InterOil interim chief executive officer Dr Gaylen Byker has previously told PNGIndustryNews.net that "major terms" had already been agreed to and that ExxonMobil wanted 4.6 trillion cubic feet of gas from the field.
The negotiations will also cover ExxonMobil-funded additional wells to further evaluate the resource.
As of late 2012, GLJ Petroleum Consultant's figures for the field included a best case estimate of 9.07Tcf of initial recoverable sales gas and 135.4 million barrels of initial recoverable condensate.
The Papua New Guinean government, another key stakeholder of the field, is using separate estimates from Gaffney, Cline and Associates.