Donald Trump's ally criticised for 'dumb' London Bridge attack tweet

An ally of US President Donald Trump's has been slammed online - including by British commentator Piers Morgan - for his response to the London Bridge terror attack.

David Wohl - the 2016 campaign surrogate for Trump - tweeted his thoughts on the attack which left two dead on Saturday morning (NZ Time).

"Takeaway from LondonBridge incident: If law-abiding Londoners could carry firearms legally, it probably wouldn't have happened.

"Amazing how bold the terrorists are when they know their victims will be unarmed."

The tweet was not well received, with many telling Wohl to focus on the United States' gun violence. 

"Focus on your own problems - goodness knows someone needs to, given the steady stream of mass shootings in the US," one user said.

"Yeah that's totally working out in the United States, right?" said another.

Journalist James Ball tweeted at Wohl saying that the murder rate in some of the United States' safest cities was still double that of London's.

"Guns are effectively illegal in London (and across the UK) and this policy is wildly popular. There is no mainstream movement to legalise handguns here," Ball wrote.

New Zealand political commentator Matthew Hooton also weighed in. 

"This is why there are never any fatal mass shootings in the United States," he said, ironically.

British television host Morgan - who won Trump's Celebrity Apprentice and has been regularly criticised for his support of the US President - even hit out at the man, asking "how can anyone be this dumb?"

Wohl replied to that tweet with his own ironic message.

"Right Piers. Having the ability to actually defend yourself from a terrorist attack is a terrible and stupid thing. 

"How can you actually be so dumb?"

The man allegedly behind Saturday's attack was shot dead by police and named by the Metropolitan Police as 28-year-old Usman Khan from England's Staffordshire. Local police confirmed he had previously been convicted for terrorism offences.

Police were assisted during the incident by members of the public who pinned Khan down and seized his knife.