London Mayor Boris Johnson was left red faced on Wednesday during a televised debate on Syria after claiming Hitler didn’t use chemical weapons during the Second World War.

Boris Johnson.

Boris Johnson.

Appearing on Channel 4’s The Last Leg, the gaff-prone mayor appeared ignorant of the Nazi Holocaust, in which millions of Jews and other “undesirables” were gassed to death, when he claimed:  “Not even Nazi Germany used chemical weapons.”

Perhaps mindful of the use of Zyklon B gas in the concentration camps, host Adam Hills pointed out: “There is an argument to say that he did use chemicals at some point.”

Johnson then added: “But in the theatre of war, as far as I can remember, and I stand to be corrected on this, I don’t believe that even the Nazis used chemical weapons.”

The Mayor also said it was a “great shame” that the UK will not be able to take action against Bashar Assad over the use of chemical weapons.

Military action against Assad over the gas attack was ruled out after David Cameron suffered a shock defeat in the Commons, but  Johnson said Britain should demonstrate its “strong revulsion”.

Johnson, who has called for a second vote in the Commons if new evidence could be presented, said the country had been “scarred” by the experience of Iraq, and he issued a fresh attack against Labour leader Ed Miliband over his decision to oppose the Government’s motion on Syria.

“As a country we have been very scarred by the experience of Iraq. There’s no question that we were deceived about what was at stake there and people don’t want to get engaged again in that way.

“It is a great, great shame that when somebody is killing large numbers of innocent people with gas, men, women and children, it is a great shame that a country like ours that stands for civilised and decent values around the world cannot do anything.

“I have to say, whatever your views about intervention, we should be able to assert our strong, strong revulsion and to make that clear to Assad.”

Johnson said he understood why a furious Downing Street described  Miliband as a “copper-bottomed s***” over his decision to oppose the Government despite  Cameron making concessions including a second vote before any UK forces began strikes against Assad.

“The question was would the Leader of the Opposition stick by what he had earlier said. I think he had indicated that he would contemplate the possibility of some calibrated, commensurate strike against the Assad regime and then he pulled the plug on it,” Johnson said.

“Clearly that’s left this country in a position where, whatever happens, it looks as though we won’t be involved.”

He added: “I can see why some unnamed Downing Street person did use that language because I would have been thoroughly hacked off too. They were led to believe that he would in principle support something that he didn’t.”