US President Donald Trump has sparked anger in France and Britain by suggesting looser gun laws could have helped prevent the deadly Paris attacks in 2015, and linking a wave of London knife crime to a handgun ban.

Key points: Trump mimicked the shooting of victims in 2015 Paris rampage, said victims should have been armed

Trump mimicked the shooting of victims in 2015 Paris rampage, said victims should have been armed France strongly criticised Trump, said it is proud of its gun regulation laws

France strongly criticised Trump, said it is proud of its gun regulation laws Trump linked knife crime in the UK to absence of guns, angered British trauma surgeons

In a speech to the National Rifle Association (NRA) on Friday (local time), Mr Trump mimicked the shooting of victims in the Paris rampage, and said if civilians had been armed "it would have been a whole different story".

The French Government issued its strongest criticism of Mr Trump since he took office, at a time when President Emmanuel Macron has been reinforcing bilateral ties following a state visit.

"France expresses its firm disapproval of President Trump's comments about the Paris attacks on November 13, 2015 and demands that the memory of the victims be respected," the foreign office said in a statement.

"Every country freely decides on its own laws on carrying firearms … France is proud to be a country where acquiring and carrying firearms is strictly regulated."

Other French politicians including the mayor of Paris took issue with Mr Trump's comments after he acted out the scene of the massacre by Islamist assailants at Paris' Bataclan concert hall, where 90 of the 130 victims of the attacks died.

"They took their time and gunned them down one by one … Boom! Come over here … Boom! Come over here … Boom!," Mr Trump said, using his hands in a gun gesture.

Former French president Francois Hollande, who was head of state at the time, said on Twitter that Mr Trump's comments and antics were "shameful" and "obscene".

French special forces evacuate people near the Bataclan concert hall following the 2015 shootings. ( Reuters: Christian Hartmann, File )

'Knives, knives, knives, knives'

Trauma surgeons in London, meanwhile, said Mr Trump had missed the point after, in the same speech, he linked knife crime there to an absence of guns.

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Comments by Mr Trump have previously caused upset in Britain.

Relations with Prime Minister Theresa May cooled last year after she criticised him for retweeting anti-Islam videos by a British far-right group.

Mr Trump told NRA members that a "once very prestigious" London hospital, which he did not name, had become overwhelmed with victims of knife attacks.

"They don't have guns … they have knives and instead there's blood all over the floors of this hospital," he said.

"They say it's as bad as a military war zone hospital … knives, knives, knives, knives," he added, making stabbing gestures.

London suffered a spike in knife crime early this year and saw more murders during February and March than New York.

Last month, trauma surgeon Martin Griffiths told the BBC that some of his colleagues had likened the Royal London Hospital in east London where he works to the former British military base Camp Bastion in Afghanistan.

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But on Saturday he indicated Mr Trump had drawn the wrong conclusion from his remarks.

Mr Griffiths posted his comment next to an animation of a stick figure with the phrase "The Point" flying over its head, and also linked to a statement on the hospital's website by a fellow trauma surgeon, Karim Brohi.

"There is more we can all do to combat this violence, but to suggest guns are part of the solution is ridiculous," Mr Brohi said in the statement on Saturday.

"Gunshot wounds are at least twice as lethal as knife injuries and more difficult to repair."

Britain's Government effectively banned handgun ownership in England, Scotland and Wales after a school shooting in Dunblane, Scotland in 1996.

May criticised Trump last year for retweeting anti-Islam videos by a British far-right group. ( AP: Matt Dunham, File )

Reuters