Britain, Germany, France and the US recently changed their rules to allow their weapons to be used by Ukraine to strike targets inside Russia to prevent a renewed invasion from the north.

Earlier on Wednesday, a Western official and US senator said Ukraine had used US weapons to bomb targets across the border, after gaining Joe Biden’s approval. The US president’s new guidance allows US arms to be used for the limited purpose of defending Kharkiv, Ukraine’s second-largest city.

Putin singled out Germany in his comments to Western journalists gathered in St Petersburg for a major economic forum, warning that the use of its weapons would mark a “dangerous step” and ruin relations between Berlin and Moscow.

“When German tanks first appeared on Ukrainian soil, it already produced such a moral ethical shock in Russia, because relations towards [Germany] in Russian society had always been very good,” he said.

“Now, when they say that some more missiles will appear that will strike targets on Russian territory, this, of course, is ultimately destroying Russo-German relations.”

In the press conference with the heads of major Western news agencies, Putin denied that he had “imperial ambitions” to expand Russia’s borders.

“They’ve come up with this idea that Russia wants to attack Nato,” he said, banging his fist on the table.

“Have you lost your mind? Are you as thick as two short planks? Who made this up? It’s nonsense, it’s b—-cks,” he said, according to an AFP translation.

“There is no need to look for some imperial ambitions of ours. There are none.”

Putin has barely addressed international journalists since Moscow sent troops into Ukraine and he has not taken questions from Western journalists since the invasion.

Russia denied for months that it was preparing a military offensive in Ukraine before launching the assault, accusing Nato powers of trying to use their Ukrainian ally to harm Russia.