"Most of you will know, while we are benefiting from the massive construction phase of our first LNG project, other sectors are being hit hard by low world commodity prices," O'Neill said at the PNG Advantage conference this week.
"The world prices for some of our major agricultural production remains depressed, especially cocoa and copra. And even industries where prices are better, such as for coffee, infrastructure and other issues remain a serious challenge.
"And in recent months, gold prices and prices for minerals generally have declined, some significantly.
"This is already having an impact on our existing mining operations and on projects at various stages of development."
The PM then said the development of PNG's natural gas resources could not be better timed.
"Even though the [PNG LNG project] construction phase is coming to an end, we will continue to benefit through strong revenue inflows to the government and export income, when construction ends and export begins," he said.
"That will deliver high GDP especially in 2015.
"Our challenge is to work with gas sector investors and developers to bring new projects to the development stage as soon as possible."
InterOil's Elk-Antelope field in Gulf province is widely expected to be the next focus for LNG commercialisation.
ExxonMobil has been negotiating to buy a 4.6 trillion cubic feet of gas slice of this field to underpin at least a third train expansion of the PNG LNG project.
However, the exclusivity arrangements of negotiations lapsed in August, allowing InterOil to restart negotiations with other previous bidders, which are believed to include French supermajor Total SA and Royal Dutch Shell.
O'Neill also revealed more about his plans to create economic hubs out of Port Moresby, Lae, Mt Hagen and tourism-focused Kokopo.
"Over the next 10 years, the focus will be on ensuring the economies of these centres can grow substantially through attracting new industries and supporting existing industries and businesses to expand," O'Neill said.
"That will require the national government, working closely with provincial and local government leaders, to provide modern and efficient infrastructure, better schools and hospitals and more reliable services such as power and water.
"It will also mean a significant expansion of housing for Papua New Guinean families who will be the main workforce in these economic centres."
O'Neill also discussed plans to foster the small to medium enterprise sector, especially to combat widespread unemployment.
"I am told Indonesia has close to 40 million small businesses," O'Neill said.
"We have not much more than 40,000! We need to multiply that number - and we need to do so as soon as is practicable.
"The government has a 12-point plan we are beginning to implement."