WikiLeaks founder Julian Assange is being held on behalf of the US authorities, as well as for breaching his bail conditions, Scotland Yard has confirmed.
The US Department of Justice said the 47-year-old had been arrested over an alleged conspiracy with Chelsea Manning “to break a password to a classified US government computer”.
He is being held in custody at a London police station after being arrested and removed from the Ecuadorian embassy on Thursday morning.
Theresa May hailed the arrest and said all MPs should welcome it.
“This goes to show that in the UK nobody is above the law,” she told parliament on Thursday afternoon.
A Scotland Yard spokesman said Assange has “been further arrested on behalf of the United States authorities, at 10:53hrs after his arrival at a central London police station”.
“This is an extradition warrant under Section 73 of the Extradition Act. He will appear in custody at Westminster Magistrates’ Court as soon as possible.”
The 47-year-old was seen shouting and gesticulating as he was carried out of the embassy in handcuffs by seven men and put into a waiting police van on Thursday morning.
As he was bundled into the van, Assange was heard shouting: “The UK must resist”.
A witness said: “He was screaming. He was struggling, I think he felt a bit weak. He was surrounded by police.”
Lenin Moreno, the president of Ecuador, said the situation had become “unsustainable” and “no longer viable”.
In a video statement he said Assange had “repeatedly violated” the conditions of his asylum in his country’s London embassy.
In a full written statement, Moreno said: “The patience of Ecuador has reached its limit on the behaviour of Mr Assange.
“He installed electronic and distortion equipment not allowed. He blocked the security cameras of the Ecuadorian Mission in London.
“He has confronted and mistreated guards. He had accessed the security files of our Embassy without permission.
“He claimed to be isolated and rejected the internet connection offered by the Embassy, and yet he had a mobile phone with which he communicated with the outside world.”
Police said Assange would remain in custody “before being presented before Westminster Magistrates’ Court as soon as is possible.
“The [Metropolitan Police Service] had a duty to execute the warrant, on behalf of Westminster Magistrates’ Court, and was invited into the embassy by the Ambassador, following the Ecuadorian government’s withdrawal of asylum.”
Foreign Secretary Jeremy Hunt praised Ecuador for its cooperation and said Assange was “no hero” and “no one is above the law”.
WikiLeaks confirmed in a tweet that Assange did not walk out of the embassy but was arrested immediately after the British police were invited into the embassy by the Ecuadorian ambassador.
Minutes later the organisation appealed for donations to its “defence fund”.
It later tweeted out an old photograph of Assange and said: “Powerful actors, including CIA, are engaged in a sophisticated effort to dehumanise, delegitimize and imprison him.”
Pamela Anderson, who famously befriended the WikiLeaks founder, tweeted her shock at his arrest.
The US actor and model called the UK “America’s bitch” and said the timing of the arrest was because the country needed “a diversion from your idiotic Brexit bullshit”.
She later added that Donald Trump was “a toxic coward” who just wanted to rally his base.
US whistleblower Edward Snowden also tweeted in support.
He said: “Images of Ecuador’s ambassador inviting the UK’s secret police into the embassy to drag a publisher of – like it or not – award-winning journalism out of the building are going to end up in the history books. Assange’s critics may cheer, but this is a dark moment for press freedom.”
Last week Wikileaks tweeted he could be expelled “within hours to days”, citing high-level sources, however the embassy denied the claims at the time.
Supporters of Assange reported increased police activity at the embassy last weekend.
Two armed officers went into the building on Saturday and people taking part in a vigil said teams of plain clothes officers were outside the embassy throughout the weekend.
A number of surveillance cameras have been positioned opposite the embassy.
In a further statement following the arrest, Hunt said: “This will now be decided properly and independently by the British legal system – respected throughout the world for its integrity – and it’s the right outcome.”
When asked what the process was that led to this between the UK and Ecuador, Hunt replied: “We have been talking to them for a very, very long time about how to resolve this situation.
“The UK is a law-abiding country – we always uphold the law, so we had to follow all the international rules in a situation like this.
“But there was a change of leadership in Ecuador, President Moreno took a courageous decision which has meant we’ve been able to resolve the situation today.
“We’re not making any judgment about Julian Assange’s innocence or guilt – that is for the courts to decide – but what is not acceptable, is for someone to escape facing justice and he’s been trying to do that for a very long time.”
Assange has feared extradition to the US since WikiLeaks published thousands of classified military and diplomatic cables.
He took refuge at the embassy in 2012 as he faced extradition from Britain to Sweden to be questioned in a sexual molestation case. He was initially welcomed as a guest.
Relations between him and the embassy have since become tense, with Ecuadorean authorities cracking down on his access to outsiders and for a time cut off his internet access.
On Thursday The Times reported that blackmailers had threatened to reveal “sexual secrets” of Assange’s life inside the Ecuadorian embassy in attempts to extort him of €3 million (£2.6 million).
WikiLeaks said that security footage and audio obtained from the site in Knightbridge had been leaked to criminals.
Kristinn Hrafnsson, editor of Wikileaks, said the information obtained by blackmailers were a “massive trove” of images and document from Assange’s lawyer.
The blackmailer identified himself to the lawyer as ‘PM’.
According to The Times, a source with knowledge of the case said: “This is how it was sold, that there was sensitive, possibly sexual, material.”
‘PM’ is threatening to sell the images to the media if the millions are not paid, according to the source.