Climate activists are "baffled" over Egypt's decision to have Coca-Cola - a major plastic producer - sponsor this year's global climate talks.
Campaigners told the BBC the deal undermines the talks, as the majority of plastics are made from fossil fuels.
Coca-Cola said it "shares the goal of eliminating waste and appreciates efforts to raise awareness".
This year's COP27 UN climate talks are hosted by the Egyptian government in November in Sharm el-Sheikh.
Egypt announced it had signed the sponsorship deal last week.
At the signing, Coca-Cola Global Vice-President, Public Policy and Sustainability Michael Goltzman said: "Through the COP27 partnership, the Coca-Cola system aims to support collective action against climate change."
But opposition to the decision has grown over the past week over Coca-Cola's links to plastic pollution. Climate activists are accusing the company of "greenwashing" and more than 5,000 have now signed a petition calling for the decision to be reversed.
The company admitted in 2019 that it uses three million tonnes of plastic packaging in a year.
Found on every continent and in the oceans, plastic is a major source of pollution. Its production also contributes to global warming. Currently 99% of global plastic is produced from fossil fuels in a process called 'cracking' which produces greenhouse gas emissions and drives climate change.
And in 2021, an audit from Break Free From Plastic named Coca-Cola as the world's number one plastic polluter.
Mohammad Ahmadi of Earth Uprising International said: "This action by the COP27 presidency goes against the purpose of the conference."
This was a sentiment echoed by Steve Trent, CEO of the Environmental Justice Foundation, who called on Egypt to reverse the decision.
Neither Egypt's COP27 presidency nor UNFCCC - the UN's climate change body - responded to the BBC's request for comment on the sponsorship deal.
Last year when the UK government hosted the climate talks, they banned fossil fuel companies from sponsoring the event.
Mr Trent said: "Coca-Cola's whole business model is predicated on fossil fuels. They have made promises to improve recycling which have never been met."
Coca-Cola told the BBC it recognised it needs to do more: "While we have made progress against our World Without Waste goals, we're also committed to do more, faster."
Climate activists the BBC spoke to were not only concerned about the signal the sponsorship sent, but also how it could affect the negotiations.
Nyombi Morris, a climate activist from Uganda and a UNOCHA Ambassador, told the BBC: "When polluters dominate climate negotiations, we don't get good results. As an African activist, I am concerned that more of our lakes are going to be filled with plastics again."
Last year the BBC revealed the impact that plastic pollution by Coca-Cola was having on remote communities across the world.
Coca-Cola told the BBC that it remains committed to: "collect and recycle a bottle or can for every one we sell by 2030."