THERESA May has scolded “unhelpful” Donald Trump for claiming the Parsons Green bucket bomber was known to Scotland Yard.

In a growing diplomatic row, the US president hit back saying the UK and America had "not been tough enough" on terror after the bomb attack in London that left 29 injured.

8 Theresa May has scolded “unhelpful” Donald Trump for claiming the Parsons Green bucket bomber was known to Scotland Yard Credit: Sky TV

8 President Trump slammed the 'terrorist losers' who carried out the bucket bomb attack

Trump has since called the Prime Minister to offer his condolences, the White House confirmed.

"The President phoned to convey his sympathies and prayers for those injured in the terrorist attack today in London", the White House said.

"The President pledged to continue close collaboration with the United Kingdom to stop attacks worldwide targeting innocent civilians and to combat extremism."

A Downing Street spokesman said: "President Trump called the Prime Minister earlier today to offer his condolences over this morning's cowardly attack in London.

"They also discussed North Korea's latest missile test, agreeing it was a reckless provocation and that China must now use all its leverage to bring pressure to bear on the North Korean regime to ensure they change course and end these illegal tests."

8 Trump has since called the Prime Minister to offer his condolences Credit: AFP or licensors

Theresa May today blasted Donald Trump's 'unhelpful' claims that the Parsons Green tube bombers were known to Scotland Yard.

In a growing diplomatic row, the US president hit back saying the UK and America had "not been tough enough" on terror after the failed bomb attack in London which left 22 injured.

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! — Donald J. Trump (@realDonaldTrump) September 15, 2017

The former Celebrity Apprentice host appeared on the lawn of the White House and briefly spoke to reporters about the "terrible" attack and need to be "very, very tough".

He said: “It's a terrible thing - it just keeps going and going and we have to be very smart, we have to be very, very tough.

“Perhaps we are not really tough enough. I’m going to call the Prime Minister right now."

Asked by reporters if he had received any intelligence about the bombing, Trump responded: “Yes I have [been briefed] on numerous things happening including North Korea.

“I’m going in right now for a briefing.”

In a series of early morning post the firebrand Republican claimed the depraved culprit had been "in the sights" of Scotland Yard in an apparent criticism of the UK security services.

In response to his comments, PM May said: "I never think it's helpful for anybody to speculate on what is an ongoing investigation."

The US President also called the terrorists “sick and demented people” in response to the assault in west London which has left 22 people injured.

He 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!”

It is not clear whether Trump was referring to intelligence he had received from the US security services or if he was speculating that Scotland Yard knew who the bombers were.

A Scotland Yard spokesman said: "The comments are unhelpful and pure speculation. If anyone has got any evidence or information, please contact the anti-terrorism hotline."

8 Trump called for a 'tougher' version of his controversial travel ban to be passed following the London bomb attack Credit: AP:Associated Press

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! — Donald J. Trump (@realDonaldTrump) September 15, 2017

The travel ban into the United States should be far larger, tougher and more specific-but stupidly, that would not be politically correct! — Donald J. Trump (@realDonaldTrump) September 15, 2017

In July, Trump confirmed the existence of a covert CIA program which funded Syrian rebels to remove dictator Bashar al-Assad from power in an astonishing tweet.

The President made the revelation while attacking the Washington Post becoming the first US President to declassify intelligence on social media.

He tweeted: “The Amazon Washington Post fabricated the facts on my ending massive, dangerous, and wasteful payments to Syrian rebels fighting Assad.”

The tweet was said to be an embarrassment to the US intelligence community which Trump has continually clashed with since he won last year’s presidential election.

Meanwhile, Trump once again called for a “tougher and more specific” form of his travel ban to be passed in the US following the Parsons Green attack.

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

What we know so far:

The property tycoon was widely criticised for tweeting out a similar plea during the London Bridge attack in June.

In the minutes following the truck assault Trump tweeted the incident was a “terror attack” despite no confirmation from UK police.

After a flurry of criticism, then White House Press Secretary Sean Spicer tweeted: “National Security team has briefed @POTUS on situation at #LondonBridge and will continue to provide updates.”

Trump then posted another message 40 minutes later calling for this travel ban to be passed through US courts.

He tweeted: “We need to be smart, vigilant and tough. We need the courts to give us back our rights.

"We need the Travel Ban as an extra level of safety!”

Latest on the Parsons Green terror attack 'grab your kids and go' Dramatic moment cops storm house in bomber hunt after man, 18, was arrested in port of Dover TERROR ON THE TUBE Chilling videos show Parsons Green terror device on fire after explosion Live Blog TUBE TERROR BLAST LIVE Britain terror threat 'critical' after explosion - follow the latest updates here 'A FIREBALL SHOT AT MY HEAD' Man caught in blast describes passengers' horror injuries and how he cowered on carriage 'WHERE'S MY BROTHER?' Young boy injured in Parsons Green terror attack was left crying out for his brother in aftermath of explosion they were RUNNING FOR THEIR LIVES Sun man caught up in Parsons Green Tube blast describes stampede as hundreds fled TRAVEL SHOCKWAVES Parsons Green explosion causes commuter chaos grinding trains and Tube to a halt 'COWARDLY ATTACK' Threat level will NOT rise but Theresa May reveals security will be ramped up on public transport TUBE BLAST Here's what we know about the Parsons Green bombing and the police investigation LONDON UNITED Cabbies offer FREE rides and Good Samaritans open up their homes to commuters caught up in Parsons Green blast

The Republican has previously tweeted out unsubstantiated claims including posting in March that former President Barack Obama had "tapped his phones" during the poisonous 2016 election campaign.

This morning, the President also said a “tougher” stance was needed and branded the internet the “main recruitment tool” for fanatics.

He tweeted: “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!”

Prime Minister Theresa May's former Chief of Staff Nick Timothy has slammed Trump's claims about Scotland Yard knowing about the attackers.

He tweeted: "True or not - and I'm sure he doesn't know - this is so unhelpful from leader of our ally and intelligence partner."

Twenty-two people have been injured including a schoolboy in the failed bucket bomb terror attack on the London Underground during this morning's rush hour.

Police are treating the blast as a terrorist incident after commuters reported a "fireball flying down a carriage" as the bomb, hidden in a Lidl bag, partially detonated inside the carriage.

Bomb squads and counter-terror cops are at the scene as it was revealed that the homemade bomb, likened pressure cooker devices used in 2013's Boston Marathon attack, did not fully detonate.

Theresa May is being keep informed of developments, in what appears to be the fifth major terror attack on British soil in six months.

8 Roads were blocked off by police as they investigated what happened on the Tube Credit: AP:Associated Press

8 A man posted a picture of his injuries after being burnt in the explosion Credit: SWNS:South West News Service

8 Armed cops were seen patrolling the streets in west London after the explosion this morning Credit: Splash News

The Prime Minister has confirmed she will chair an emergency meeting of Cobra this afternoon.

She tweeted: My thoughts are with those injured at Parsons Green and emergency services who are responding bravely to this terrorist incident."

The attack follows four previous attacks in the UK capital over the last six months.

An onlooker said a "fireball flew down a carriage" with panicked commuters diving out an open door at the South West London station.

A picture taken on the District Line train shows a burning plastic bucket with what appear to be wires coming from it.

8 This woman was seen bandaged up after the shocking attack this morning Credit: Reuters

The blast is believed to have come from the suspected device, which had been placed in a foil lined Lidl cool bag and left by the tube carriage door.

London Ambulance Service said 18 people have been taken to hospital, none of who are suffering life-threatening injuries.

It is believed a young boy is among the worst injured with witnesses reporting he had serious burns to his legs.

It is believed some of those injured may have been caught in the crush as panicked commuters fled the station.

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