A week of United Nations negotiations over a treaty to end global plastic pollution closed on Friday with many ideas and few decisions, as participants begin the work needed to produce the first legally binding treaty on the issue by the end of 2024.

The meeting in the coastal city of Punta del Este, Uruguay was the first of a number of planned sessions that include 160 countries. Opening the negotiations, Peruvian chair Gustavo Meza-Cuadra said the eventual agreement would be “the most significant international environmental treaty of recent years.” In a tweet on the final day of the meeting, UN Secretary General António Guterres called plastics “fossil fuels in another form.”

Ideas shared by delegates over the course of the week included calls for toxic substances in plastics to be banned and a reduction in production and usage. Plastics industry groups have called for a focus on recycling, while a cap on virgin plastic production was backed by businesses including Unilever and Nestle, two of the most significant contributors to plastic waste, according to audits carried out by the campaign group Break Free From Plastic.

But the exact contents of the agreement is still yet to be determined, and the first week of negotiations was dominated by procedural questions over voting arrangements and the model the treaty should follow.

The last point has already become one of contention as campaigners seek to avoid a repeat of the 2015 Paris Agreement on climate change, which allows countries to set their own goals and plans to reduce greenhouse gas emissions. The United States and Saudi Arabia are advocating to take a similar approach with a global plastics treaty. Others, including the European Union, host Uruguay and small island states that are particularly negatively affected by the problem of ocean plastic, pushed for a global set of rules including controls on production.

Environmental groups said a failure to set global standards would produce a weaker agreement. “We haven’t really seen much success coming out of the Paris Agreement,” said Chris Dixon, ocean campaign leader at the UK-based Environmental Investigation Agency, an NGO. “So why on earth would we be trying to negotiate a new convention which is modeled on something that’s essentially been a failure?” Dixon said a “common global objective” is needed.

In a statement, WWF global plastics policy lead Eirik Lindebjerg called the meeting a “promising start,” adding: “The next stage of negotiations will be more challenging, as countries must agree on the technical measures and rules.”

Negotiators are next expected to meet in April 2023 in Paris.