Protest groups gathered in central London after the anniversary of Russia’s invasion of Ukraine

Mr Tatchell shouted “Chamberlain” – a reference to Prime Minister Neville Chamberlain’s policy of appeasing Adolf Hitler nazi regime – in response to protesters who angrily accused him of “American puppet”.

He was one of a group of 30 people who disrupted a rally by the Campaign for Nuclear Disarmament (CND) and the Stop the War coalition outside the BBC.

His fellow protesters chanted “arms, arms, arms to Ukraine, put an end to (Russian President Vladimir) Putin’s administration” and “Self-defense is not a crime.”

Mr Tatchell told the PA news agency: “We are here to protest Stop the War against its actions against Ukraine. Their position will leave Ukraine defenseless and lead to Russia occupying and annexing all of Ukraine.

“Russia is a fascist, imperialist state, and all progressive people must oppose Putin’s regime and the Russian war of aggression.

“We must arm Ukraine in the same way we armed the anti-Nazi resistance during World War II. This is a war between Ukrainian democracy and Russian fascism.”

His group held a banner with the inscription “Victory to Ukraine, arm Ukraine to defeat Russian imperialism.”

CND and Stop the War argue that Russia’s invasion was partly prompted by “NATO expansion” in Eastern Europe.

Their protesters held placards reading ‘Peace Now!’, ‘No War’ and ‘Wages Not Guns’, with one man flying an inflatable anvil that read: ‘Is this anvil really cast iron? Is there an alibi for the Biden gang?”

Stop the War organizer Terina Hein, 54, said Ukraine would become the “Afghanistan of Europe” unless she and her supporters stop “backing Putin into a corner”.

She told PA: “If we continue to corner Putin, there is a very high possibility that this will escalate to the nuclear level.

“Most likely, the war will be very long and very protracted, and if it continues as it has so far, it will lead to thousands and thousands of deaths and turning Ukraine into the Afghanistan of Europe.

“The war will eventually end with peace negotiations. So why not do it now?

“Anyone who even dared to mention anything to that effect was accused of being a traitor, a conciliator, or any of those other terms that are used as a line of attack against people who just want peace.”

Tom Unterreiner, 42, chairman of the CND, said talks were inevitable and argued there was no reason to delay them.

He told PA: “Everybody knows it will end in negotiations. Everyone knows that this will end in diplomacy.

“So the only question now is how much destruction there will be in Ukraine, how many Ukrainians will die and how close we will come to the nightmare of using nuclear weapons.

“Given that there is widespread recognition that this conflict will end in negotiations, given the nuclear threat so acute, now is the time for negotiations. We don’t have time to wait.”

The Met Police have been contacted for comment.