French President Emmanuel Macron has called Polish PM Mateusz Morawiecki "a far-right anti-Semite who bans LGBT people", after being criticised for his talks with Russia's Vladimir Putin, reports BBC News.
Mr Morawiecki compared Mr Macron's efforts to negotiating with Hitler.
The French president has held regular conversations with Mr Putin since the beginning of the conflict in Ukraine.
On Friday, Poland summoned the French ambassador over Mr Macron's comments, made to a French newspaper.
"How many times have you negotiated with Putin and what have you achieved?" Mr Morawiecki said on Monday.
Mr Macron defended the talks in an interview with Le Parisien newspaper.
"It's my duty to speak with him, we need it. I won't stop doing it, that's what allows us to take part in the negotiation," he said.
"By talking to him and to [Ukraine's] President Zelensky, we can help in the negotiation. At some point, there will be a ceasefire and peace will have to be built. It cannot be done without a guarantor, France is committed to be one of these guarantors."
It is not clear why Mr Macron accused Mr Morawiecki of anti-Semitism, although the Polish government has faced international criticism for laws making it harder for Jewish people to recover property lost during and after World War Two, as well as one making it an offence to link the Polish nation to Nazi crimes.