France and Ireland say they will not ratify a huge trade deal with South American nations unless Brazil does more to fight fires in the Amazon.
French leader Emmanuel Macron said President Jair Bolsonaro had lied to him about his stance on climate change.
There are currently a record number of fires in the Amazon rainforest – a major source of oxygen for the world.
Environmental groups say the fires are linked to Mr Bolsonaro’s policies, which he denies.
European leaders have also expressed dismay over the fires, with UK Prime Minister Boris Johnson saying he is “deeply concerned” about “the impact of the tragic loss of these precious habitats”.
German Chancellor Angela Merkel has called the fire an “acute emergency… shocking and threatening not only for Brazil and the other affected countries, but also for the whole world”.
Mr Bolsonaro said on Friday that he was considering options for fighting the fires, including deploying the military.
However, he has also accused Mr Macron of meddling for “political gain”, and previously said calls to discuss the fires at the G7 summit in Biarritz, France – which Brazil is not participating in – showed “a misplaced colonialist mindset”.
Mr Macron, and Ireland’s Prime Minister Leo Varadkar, now say they will not ratify the EU-Mercosur trade deal unless Brazil shows a commitment to protecting the environment.
The trade deal – which took 20 years of negotiation to reach – was agreed between the EU and a South American bloc consisting of Argentina, Brazil, Uruguay and Paraguay.
It has been described as the EU’s biggest deal to date – and would cut or remove trade tariffs on both sides, giving EU firms that make industrial products and cars access to Mercosur, and helping Mercosur countries export farm products, including beef, sugar, and poultry, to the EU.
Amazon fires: France and Ireland threaten to block EU trade deal