British Prime Minister Theresa May has rebuked US President Donald Trump for claiming suspects in Friday’s London train blast were known to police.
“I never think it’s helpful for anybody to speculate on what is an ongoing investigation,” she said.
Mr Trump described the attackers in a tweet as “loser terrorists” and “sick and demented people who were in the sights of Scotland Yard”.
The bomb rocked a London Underground train on Friday, injuring 22 people.
In a phone call with Mrs May on Friday, Mr Trump “pledged to continue close collaboration with the United Kingdom to stop attacks worldwide targeting innocent civilians and to combat extremism”, the White House said.
A Downing Street spokesman said he also offered “his condolences over this morning’s cowardly attack in London”, which he described to reporters earlier as “a terrible thing”.
The call came after Mrs May’s comments, and after the US President had been widely criticised for his tweets.
In one, he appeared to chide UK authorities: “Must be proactive!”
London police said of the US president’s remarks that “any speculation is unhelpful”.
Mr Trump’s tweets sparked anger on the social network, where Nick Timothy, a former senior aide to British Prime Minister Theresa May, echoed London police’s comments.
“True or not – and I’m sure he doesn’t know – this is so unhelpful from leader of our ally and intelligence partner,” he said.
Former Conservative lawmaker Ben Howlett also weighed in, calling Mr Trump’s tweets “dangerous and inappropriate”.
In a series of tweets on Friday, the Republican president claimed his administration had “made more progress in the last nine months” against the so-called Islamic State than his predecessor, Barack Obama.
“Must be proactive & nasty!” he tweeted.
Analysis: Changing the subject
Anthony Zurcher, BBC News Washington
Last month Donald Trump defended his delay in ascribing blame for the violence at a white nationalist rally in Charlottesville by saying: “I wanted to make sure, unlike most politicians, that what I said was correct, not make a quick statement.”
That is advice the president seemed uninterested in heeding on Friday morning, as he fired of a series of tweets reacting to the London train incident.
In fact, with few exceptions, Mr Trump is happy to quickly react to international incidents he suspects are perpetrated by Islamic militants, even when – in the case of the Philippines casino robbery – that’s not the case.
The president’s twitter feed on Friday morning was peculiar, although not necessarily surprising. Besides his London remarks, he again blasted Senate procedural rules, called for his Muslim travel ban to be “tougher”, said the fight against the so-called Islamic State should be “nasty”, and slammed ESPN, a US sports cable network, for being too political.
Given that Mr Trump was under fire from his base on Thursday for reaching out to Democrats and being too conciliatory on immigration, it is hard not to think that his actions on Friday may be an effort to change the subject.
Mr Trump also renewed a call to shut down internet capabilities, which he said were a main recruitment tool for terrorists.
During the Republican presidential campaign in 2015, Mr Trump suggested he would ask Microsoft founder Bill Gates to cut off the internet because of terror recruitment.
“We’re losing a lot of people because of the internet,” Mr Trump said at the time, without elaborating. “We have to see Bill Gates and a lot of different people that really understand what’s happening.”
“We have to talk to them about, maybe in certain areas, closing that internet up in some ways,” he added.
Friday was not the first time Mr Trump has been accused of reacting to suspected terrorist incidents before the facts are fully known.
If he was leaking sensitive information on Friday, and not indulging in pure speculation as London police say, his tweet could amount to a security breach.
In May, US officials angered British authorities, when details about a deadly bomb attack at an Ariana Grande concert in Manchester were leaked to American media.
The attacker’s identity and details of the investigation were revealed in US media before British authorities made the information public, while the New York Times published photographs from the scene, as well as images of the bomb.
The president also used Friday’s attack to promote his travel ban temporarily barring people from six Muslim-majority countries as well Syrian refugees from entering the US.