US President Donald Trump triggered a barrage of furious criticism for his response to the terror attack on a crowded London tube train on Friday (15 September) after he claimed the "loser terrorist" responsible for it was "in the sights of Scotland Yard". The explosion on the London Underground at Parsons Green injured 29 people.

Isis has claimed responsibility for the sixth attack in Britain this year.

In a flurry of early morning tweets shortly after the explosion, Trump wrote: "Another attack in London by a loser terrorist. These are sick and demented people who were in the sights of Scotland Yard. Must be proactive!

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

When the president tweeted, UK officials had not released information regarding the suspect or whether they were on local law enforcement's radar. No group or individual claimed responsibility for the blast at the time either.

In a separate tweet, Trump reiterated his call for the controversial travel ban in the US "to be far larger, tougher and more specific". However, he added: "Stupidly, that would not be politically corrected."

"We have made more progress in the last nine months against Isis than the Obama Administration has made in 8 years. Must be proactive & nasty!" he continued.

British officials later rebuked Trump over his remarks, particularly about Scotland Yard, with Prime Minister Theresa May saying: "I never think it's helpful for anybody to speculate on what is an ongoing investigation." The Met police also said the president's comments on the incident were unhelpful and "pure speculation".

Twitter immediately slammed Trump over his "grotesque" remarks following the attack saying the president "once again jumped to conclusions without checking the facts first".

"True or not - and I'm sure he doesn't know - this is so unhelpful from leader of our ally and intelligence partner," Nick Timothy, former chief of staff to Prime Minister May tweeted. Another person tweeted: "With Trump at the helm is the US really our ally now? Where is is message of sympathy and solidarity?"

"Whenever an ally is attacked, the world can count on President Trump to criticise that ally!" one Twitter user wrote.

Many people also criticised Trump for using the attack to advocate his controversial travel ban barring travellers from several Muslim-majority countries from entering the US. Some also compared his quick response to the latest terror attack to his "slow, muddled response" after the violent Charlottesville protests.

"Stop the KKK before you DARE to comment on this great country," Eve Myles tweeted. "Nasty horrid rich kid."

Others slammed him for claiming his administration made more progress against Isis than his predecessor Barack Obama did in eight years.

"Someone needs to tell him it's OK, we'll never mistake him for Obama. Trump is not intelligent, diligent, informed, humane or good-looking," one Twitter user wrote. Another added: "You will never be half the man that Obama is, deal with it!"

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Twitter blasted US President Donald Trump over his remarks on the London Underground attack Jeff J Mitchell/Getty Images