The French president, Emmanuel Macron, has condemned what he called “extraordinarily rude” comments made about his wife, Brigitte, by the far-right Brazilian leader, Jair Bolsonaro, escalating their diplomatic clash.

“He has made some extraordinarily rude comments about my wife,” Macron said at a press conference at the G7 summit in Biarritz when asked to react to statements about him by the Brazilian government.

“What can I say? It’s sad. It’s sad for him firstly, and for Brazilians,” he added.

Over the weekend Bolsonaro personally expressed approval online for a Facebook post implying that Brigitte Macron was not as good-looking as his own wife, Michelle Bolsonaro.

A Bolsonaro supporter posted: “Now you understand why Macron is persecuting Bolsonaro?” next to an unflattering picture of Brigitte Macron, 65, who is 28 years older than Bolsonaro’s wife, Michelle. Bolsonaro himself replied on Facebook: “Do not humiliate the guy, ha ha.”

Macron said: “I think Brazilian women will probably be ashamed to read that from their president. I think that Brazilians, who are a great people, will probably be ashamed to see this behaviour … And as I feel friendship and respect towards the Brazilian people, I hope that they will very soon have a president who behaves in the right way.”

Since forest fires swept through the Amazon this month, Macron and Bolsonaro have been locked in a war of words seen as the worst diplomatic crisis between France and Brazil in 40 years.

Macron tweeted of the Amazon blazes: “Our house is literally on fire”, calling it a global crisis and criticising Brazil’s management of the Amazon.

France accused Bolsonaro of lying to Macron over his commitment to combating the climate emergency, saying Paris would no longer support the Mercosur deal with Brazil, Argentina, Uruguay and Paraguay.

Q&A What is Mercosur? Show Mercosur, officially known as the southern common market, is a South American trading bloc. It was formed in 1991 by the treaty of Asunción signed between Argentina, Brazil, Paraguay and Uruguay. The aim of Mercosur is to make trade and economic development easier between the nations by removing tariffs and forming a customs union, similar to the European Union’s single market. Mercosur also negotiates free trade agreements on behalf of member states. With a combined GDP of nearly $3.5tn, Mercosur can claim to be the fifth largest economy in the world, representing a population of more than 295 million. Bolivia is in the final stages of joining the group, and Venezuela is a full member but is currently suspended. Chile, Colombia, Ecuador, Guyana, Peru, and Suriname are associate members, giving them preferential access to the market without being part of the customs union or having any voting rights. The supra-national Mercosur parliament first sat in 2007 but it only has advisory powers over the common market council, which is Mercosur’s highest decision-making body.

Macron pointed out that the French overseas territory of French Guiana on the northern coast of South America is France’s biggest land border, so the Amazon was particularly important for France because “we are there”.

Bolsonaro then publicly attacked Macron for what he called a “colonialist mentality”.