U.S. President Donald Trump has used the latest terrorist attack in London to promote his Muslim ban on residents of six Muslim-majority counties.

“Another attack in London by a loser terrorist,” Trump tweeted, hours after an explosion occurred in the London subway system.

He added: “The travel ban into the United States should be far larger, tougher and more specific – but stupidly, that would not be politically correct!”

He later said the U.S. must be “smarter” when it comes to terrorism.

“It’s a terrible thing,” he said of the London attack. “It keeps going and going, and we have to be very smart and we have to be very, very tough – perhaps we’re not nearly tough enough.”

Trump has on many occasions used terrorist attacks to promote his Muslim ban, which came under the name “Executive Order Protecting The Nation From Foreign Terrorist Entry Into The United States”.

Following Friday’s attack, which injured 22 people, Trump tweeted that the terrorists must be “dealt with in a much tougher manner”. He also advocated for a “larger, tougher” ban and suggested shutting down the internet.

“Loser terrorists must be dealt with in a much tougher manner,” he wrote. “The internet is their main recruitment tool which we must cut off & use better!”