Donald Trump’s tweets in response to the London Bridge terror attack could foreshadow a dictatorial reaction by the US leader to attacks on American soil, a former speechwriter for Barack Obama has suggested.

Following the truck and knife attack in the UK that left at least seven people dead and 48 people injured, Mr Trump tweeted “we must stop being politically correct and get down to the business of security for our people. If we don't get smart it will only get worse.”

The President also criticised the Mayor of London, Sadiq Khan, for saying there is “no reason to be alarmed”, apparently after hearing the comment taken out of context on Fox News.

Mr Trump was responding to remarks made by Mr Khan on Sky News, in which the mayor advised the public not to be concerned if they saw more police on the streets of London over the next few days.

“No reason to be alarmed – one of the things the police and all of us need to do is make sure we’re as safe as we possibly can be,” the mayor said.

In another tweet, Mr Trump wrote: “Do you notice we are not having a gun debate right now? That's because they used knives and a truck!”

Jon Favreau, who served as the White House Director of Speechwriting under President Obama, tweeted in response: “It's hard to read Trump's tweets this morning and not think that we're one domestic attack away from the most dangerous version of this guy.”

In another series of tweets on Monday morning, Mr Trump called for a tougher executive order on immigration intended to temporarily bar citizens of six predominantly Muslim countries from entering the US.

The President declared that the Justice Department should have fought for his original order, instead of the “watered down, politically correct version” that has been submitted to the Supreme Court.

The Trump administration dropped its appeal of the President’s first travel ban issued in January, after the US Court of Appeals for the Ninth Circuit in California deemed the order unconstitutional.

Mr Trump then issued a heavily revised ban in March aimed at defeating court challenges, but has still not been successful.

Last month, the US Court of Appeals for the Fourth Circuit in Virginia upheld the block on the order, a decision that the administration is now appealing against to the Supreme Court.