BUSAN, South Korea -- Negotiators on a treaty to curb plastic pollution face tough debate on the last day of scheduled talks, as over 100 countries support curbing production while a handful of oil-producing countries want to focus only on plastic waste.

The fifth and final U.N. Intergovernmental Negotiating Committee meeting to yield a legally binding global treaty is set to wrap up in Busan, South Korea, on Sunday, but a final plenary session has not been set.

A treaty could be the most significant deal relating to environmental protection as well as climate-warming emissions since the 2015 Paris Agreement.

Countries remained far apart on Sunday on the basic scope of the treaty. An option proposed by Panama, backed by over 100 countries, would create a path for a global plastic production reduction target, while another proposal does not include production caps.

"If you're not contributing constructively, and if you're not trying to join us in having an ambitious treaty... then please get out," Fiji's chief negotiator, Climate Minister Sivendra Michael, told a press conference.

A smaller number of petrochemical-producing nations such as Saudi Arabia have strongly opposed efforts to target plastic production and have tried to use procedural tactics to delay negotiations.

Saudi Arabia did not have an immediate comment.

China, the United States, India, South Korea, and Saudi Arabia were the top five primary polymer producing nations in 2023, according to data provider Eunomia.

Hours remaining

With just hours remaining for scheduled talks and consensus seemingly out of reach, some negotiators and observers fear the talks could collapse or be extended to another session.

Even if a legally binding treaty is not reached at Busan, "this is a multilateral process that can keep working towards that goal," Mexico's head of delegation, Camila Zepeda, told Reuters.

"We have... a coalition of the willing, over a hundred countries that want this, and we can start working together" on a way forward.

Plastic production is on track to triple by 2050, and microplastics have been found in air, fresh produce and even human breast milk.

The chair of the meeting, Luis Vayas Valdivieso, released a revised document on Sunday that could form the basis of a treaty.

But the text remained peppered with many options on the most divisive issues: capping plastic production, managing plastic products and chemicals of concern, and financing to help developing countries implement the treaty.

Chemicals of concern in plastics include more than 3,200 found according to a 2023 U.N. Environment Programme report, which said women and children were particularly susceptible to their toxicity.

"If it (the text) does not have the provisions of what we expect from an ambitious treaty, then we will.. go back to the same process pushing for an ambitious treaty," Sivendra said.

"Nobody is going to leave Busan with a weak treaty."