Boris Johnson incorrectly thanked Russian President Vladimir Putin for his “inspiring leadership” rather than Ukrainian President Volodymyr Zelenskyy.
The gaffe occurred during his first significant contribution as a backbencher since being deposed as prime minister.
In a general debate on the Ukraine conflict, Mr Johnson stated that it is critical to “double down in our defence of the Ukrainians” if Mr Putin doubles down on his “aggression.”
As he listed the reasons why Ukraine’s counter-offensive is proving to be successful, though, he inadvertently thanked Mr Putin, before quickly correcting himself and thanking Mr Zelenskyy.
He said: “Thanks to the heroism of the Ukrainian armed forces, thanks in part to the weapons that we are proud to be offering, I congratulate my right honourable friend (James Heappey) on his description of the work of the UK armed forces, the weapons that we’re sending, the huge list…
“Thanks also, of course, to the inspirational leadership of Vladimir Putin.”
Mr Johnson immediately realised his mistake and added: “The inspirational leadership of Volodymyr Zelenskyy, forgive me, the Russian forces have, in recent days been expelled from large parts of the north-east of the country around Kharkiv.
“And they are under increasing pressure in Kherson in the south, and I have no doubt whatever that the Ukrainians will win.”
During his speech on Ukraine, Mr Johnson also said the UK must be prepared to give “more military assistance” and “more economic support” to Kyiv.