Being held at a central London police station, Assange would be presented before the Westminster Magistrates' Court "as soon as is possible", the Metropolitan Police Service (MPS) said in a statement.
Assange, 47, was arrested on behalf of the US after receiving a request for his extradition, it added. Another reason for his detention was that he failed to surrender to the court, the police added.
In a statement, the UK Home Office said, "We can confirm that Julian Assange was arrested in relation to a provisional extradition request from the US. He is accused in the US of computer related offences."
Assange surrendered to the British police in 2012 and was released on bail within 10 days after a drama that began in November 2010 when Sweden issued an international arrest warrant for him over allegations of sexual assault and rape.
Dramatic footage posted online shows a bearded Assange shouting as he was carried by seven police officers out of the Embassy and bundled into a police vehicle.
Denying the allegations, Assange claimed he would be extradited from Sweden to the US because of his role in publishing US diplomatic cables. Sweden had rescinded its arrest warrant, but prosecutors had stressed that the case was not closed and could be picked up again.
"The most recent incident occurred in January 2019, when WikiLeaks leaked Vatican documents. This and other publications have confirmed the world's suspicion that Assange is involved in interfering in internal affairs of other states," Moreno said.
His accusations against Assange also included blocking security cameras at the embassy, accessing security files and confronting guards. He also "threatened Ecuador" two days ago through Wikileaks, according to Moreno.
Scotland Yard said it was invited into the embassy by the ambassador, following the Ecuadorian government's withdrawal of asylum. But WikiLeaks tweeted that Ecuador had acted illegally in terminating Assange's political asylum "in violation of international law".
"Assange's critics may cheer, but this is a dark moment for press freedom," said Whistleblower and fugitive Edward Snowden.
UK Foreign Minister Alan Duncan said the arrest followed "extensive dialogue between our two countries". Sweden's Chief Prosecutor Ingrid Isgren said: "We do not know why he is under arrest. We are following the developments."
However, the Swedish woman who had made the allegations against Assange welcomed his arrest.
Assange rose to international attention in 2010 after WikiLeaks published leaked military information, provided by former US Army soldier Chelsea Manning, which prompted the American government to launch a criminal investigation into the publisher.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)