Vladimir Putin told the West to “go to hell” on nuclear arms reduction as he confirmed that atomic weapons have already been deployed to Belarus.

The Russian President, speaking at the annual St Petersburg Economic Forum, said: “We have more nuclear missiles than Nato countries, and they want to reduce our numbers”.

“Go to hell,” he said, to applause from visiting delegates.

The unusually foul-mouthed remarks came during a three-hour speech at the event once dubbed “Russia’s Davos”, which this year featured strongmen tearing apart tennis balls among a host of bizarre vignettes.

Putin said the “first part” of a nuclear weapon had been delivered to Belarus, with the process set to be complete by summer. It will mark the first time Moscow has deployed nuclear weapons outside its borders since the fall of the Soviet Union. Russia is “theoretically” ready to fire an atomic weapon if its territorial integrity is threatened, Putin said.

In another warning to the West, the 70-year-old Russian leader suggested Moscow may strike F-16 jets meant for Ukraine, even on Nato soil.

“F-16 aircraft will burn like these tanks,” he said, referring to Russian strikes on German Leopard II tanks. “If they are based in air bases in other countries but are used in Ukraine then we will have to think carefully about where to hit them.” Ukraine’s western allies, including Britain, are training pilots on the fifth-generation fighter jets, with delivery to the battlefield possible within six months.

Guests at the forum, which once included western business elites, were mainly drawn from Russia’s few remaining allies, including Cuba and Syria. The guest of honour was Algeria’s President and the host was Dimitri Simes, an ethnic Russian US citizen who has become a cheerleader for the Kremlin.