The French parliament was brought to a halt after a far-right MP shouted “They should go back to Africa” as a black colleague talked about immigration.
Grégoire de Fournas, a member of National Rally (RN), said later his remark had not been aimed at Carlos Martens Bilongo himself but at migrants trying to reach Europe by sea.
Mr Bilongo said he had been born in France and the remark was “shameful”.
Prime Minister Elisabeth Borne said there was “no room for racism”.
The National Assembly’s bureau would meet on Friday and decide on the “necessary sanction”, the liberal politician told reporters.
Mr Bilongo had been questioning the government about a request by the SOS Méditerranée non-governmental organisation for help in finding a port for 234 migrants rescued at sea in recent days.
When Mr de Fournas made his remark, the Speaker, Yael Braun-Pivet, demanded to know who had spoken. Then, as MPs chanted “Out! Out! Out!”, she suspended the session, declaring, “This is not possible.”
Mr Bilongo, an MP from the the left-wing party France Unbowed (LFI), said: “Today it’s come back to the colour of my skin. I was born in France, I am a French MP.”
Mr de Fournas tried to defend himself, saying he had been referring to the “boat transporting migrants to Europe” but he later apologised to Mr Bilongo for “the misunderstanding” his comments had caused and if he had been hurt by them.
LFI leader Jean-Luc Mélenchon tweeted that the MP’s comments were “beyond intolerable” and he should be kicked out of the National Assembly.
Immigration featured prominently in the RN’s presidential and parliamentary election campaigns this year, with party leader Marine Le Pen proposing a referendum on major reductions in immigration if she became president.
In the parliamentary election in June, the party increased its presence in the National Assembly tenfold, winning 89 seats.