Host Azerbaijan tried to bring down the diplomatic temperature in Baku on Thursday after a French minister cancelled her trip to the UN climate talks and Argentina withdrew its delegation.
While negotiators work behind closed doors at the COP29 talks to thrash out a climate finance deal, the spotlight has been largely stolen by diplomatic turmoil.
France's Environment Minister Agnès Pannier-Runacher said Wednesday she would not travel to Baku after Azerbaijan's President Ilham Aliyev accused Paris of colonial "crimes" and "human rights violations" in its overseas territories.
Pannier-Runacher called his speech "unacceptable... and beneath the dignity of the presidency of the COP."
Attempting to calm the waters on Thursday, COP29 lead negotiator Yalchin Rafiyev insisted that Azerbaijan had fostered "an inclusive process".
"We have opened our doors to everybody to come to engage in very constructive, fruitful discussions," he told reporters.
"Our doors are still open."
Relations between Paris and Baku have long been tense over France's support for Azerbaijan's arch-rival Armenia.
Azerbaijan defeated Armenia in a lightning offensive last year when it retook the breakaway Armenian-populated region of Nagorno-Karabakh -- leading to an exodus of more than 100,000 Armenians.
'Diplomatic matter'
Aliyev has hailed the victory in remarks to delegates and also raised eyebrows by insisting natural resources including carbon-emitting fossil fuels were a "gift from God".
The EU's climate commissioner said the climate talks "should be a place where all parties feel at liberty to come and negotiate."
"The COP Presidency has a particular responsibility to enable and enhance that," Wopke Hoekstra posted on X.
Compounding the diplomatic turmoil, Argentina's delegation was abruptly pulled from the talks.
An environment ministry source confirmed the departure but declined to offer more detail.
Argentina's anti-establishment President Javier Milei has made no secret of his scepticism of climate change and is an ally of newly reelected former US president Donald Trump.
While Argentina's delegation was small, its departure "is unprecedented in the country's diplomatic history", said Oscar Soria, an Argentine environmental activist and director of the Common Initiative.
Rafiyev declined to be drawn on the departure.
"We hope that all who are attending here have only one intention, to come to join us in this collective effort to get an outcome that is positive," he said.
'Very worried'
But progress on the key goal of the talks -- a new climate finance deal -- is proving grindingly slow.
The main fault line is clear: how much should developed countries pay to help poorer nations adapt to climate change and transition away from fossil fuels.
Rich nations are reluctant to increase the US $100-billion a year already committed, conscious of domestic publics angry about inflation and stuttering economies.
But developing countries warn they need at least US $1 trillion to defend against the ravages of climate change and meet commitments to reach net-zero emissions.
Sources described ongoing discussions as difficult, with negotiators struggling to wrestle a draft text into a reasonable form before ministers arrive in a few days to start nailing down a deal.
The EU's lead negotiator Jacob Werksman said he was "very worried" about the slow process."
"We are way off a landing ground."
Hanging over proceedings is the question of what role the United States will play on climate action and funding after Trump returns to the White House in January.
He has pledged to again withdraw from the landmark Paris agreement, raising questions about what US negotiators can deliver in Baku.
"I think it's fair to say that there's some uncertainty in the next administration," conceded Jake Levine, the White House's senior director for climate and energy.
But the need to "project American values" would be a powerful driver for continued climate funding and action, he added.
"We cannot cede the playing field to China, to our competitors... So I think that you will see a continued American presence."
by by Delphine Paysant / Laurent Thomet