Voicing concern over the "Brazilian president's actions", Merkel said she would "take the opportunity at the G20 summit for straight talk because I find what's happening at the moment in Brazil dramatic."

She was replying to a question in parliament over deforestation in the Latin American nation.

Tensions are growing over the Amazon as illegal loggers, clandestine miners and aggressive farming businesses appear to have found their champion in Bolsonaro.

Hundreds of activist groups earlier this month urged the EU to "immediately halt negotiations" for a trade deal with Mercosur countries over Brazil's alleged harm of its indigenous people and rainforests.

The appeal from more than 340 groups could further complicate the European Union's bid to conclude 20 years of talks for a free trade agreement with Brazil and its Mercosur partners Argentina, Uruguay and Paraguay.

Merkel said she would not seek to put the talks on hold over the deforestation.

"I think that not concluding the Mercosur deal would not have led to one hectare less of deforestation in Brazil. On the contrary," she said.

"That's why I think that not concluding the deal is not the answer to what's happening in Brazil."