Julian Assange is facing extradition to the US following his arrest at the Ecuadorean embassy in London, charged with involvement in a computer hacking conspiracy that led to one of the “largest compromises of classified information in US history”.

Hours after he was carried out of the mission in Knightsbridge by police, the WikiLeaks founder was found guilty at Westminster Magistrates’ Court of jumping bail on a 2010 extradition order to Sweden. Mr Assange faces up to 12 months in prison.

The US authorities are seeking the extradition of the 47-year-old activist, alleging that he helped former US army intelligence analyst Chelsea Manning leak a treasure trove of official US documents and communications in a scandal that became known as “Cablegate”.

The US justice department indictment, filed in March 2018 but unsealed on Thursday, accused Mr Assange of helping Ms Manning to try to crack a password to Pentagon computers.

Mr Assange’s arrest ends a seven-year saga that has pitted international legal authorities against one of the most controversial transparency advocates. He has claimed that the original case against him in Sweden over an alleged rape has been part of a US-led conspiracy.

Mr Assange’s US lawyer, Barry Pollack, said the arrest raised serious issues over the ability of advocates and journalists to uncover government wrongdoing, and called the US case “unprecedented”.

“While the indictment against Julian Assange disclosed today charges a conspiracy to commit computer crimes, the factual allegations against Mr Assange boil down to encouraging a source to provide him information and taking efforts to protect the identify of that source,” he said.

If found guilty on the American charges, Mr Assange faces a maximum prison sentence of five years, the US justice department said.

Swedish prosecutors said they would now examine a request by the lawyer of Mr Assange’s alleged victim to restart their investigation. They noted that they were able to reopen the probe until next August under Sweden’s statute of limitations for rape.

London’s Metropolitan Police were able to seize Mr Assange after Ecuador lifted its asylum protection and invited British authorities into the embassy. Ecuador’s president, Lenín Moreno, said in a video statement that the country had withdrawn diplomatic protection because Mr Assange had flouted the conditions of the arrangement, recently exhibiting “discourteous and aggressive behaviour”.

WikiLeaks said in a Twitter statement that the termination of Mr Assange’s asylum was “illegal”, while Russian officials, who have spoken out in defence of Mr Assange during his time in the embassy, on Thursday described his treatment as a “witch hunt”.

“The whole story, with the persecutions against him, the witch hunt, the creation of inhumane conditions of existence, obliterates freedom of speech and the right to disseminate information,” said a foreign ministry spokesperson, Maria Zakharova. “This is a blow to the rights of a journalist. And there can be no other assessment.”

Jennifer Robinson, UK lawyer for Mr Assange, said of the US charges: “This is a dangerous precedent for the media worldwide . . . What this means is that any media organisation or journalist anywhere in the world could face extradition and prosecution for publishing truthful information about the US.”

She said that from the start of the Swedish investigation Mr Assange had been worried that the US was preparing charges. “We have always been concerned that this case is and has always been about the risk of extradition to the US. He was always happy to answer the Swedish investigation and in fact we offered his testimony for years.”

She added there were concerns over any trial that Mr Assange might face in the US. “In the context of a case which has been so politicised over so many years we are very concerned about whether he would get a fair trial in the US . .. ”

The WikiLeaks founder was granted asylum in the embassy in 2012 after Sweden requested extradition in the rape investigation. Swedish authorities dropped the case in 2017 because his diplomatic protection meant that they could not carry out their European arrest warrant.

Scotland Yard moved to arrest Mr Assange soon after Mr Moreno revoked his asylum on Wednesday, according to Whitehall officials close to the negotiations.

Mr Moreno’s election two years ago gave the UK government the opportunity to open new discussions with Quito on how to end the asylum agreement that had been granted by his predecessor, Rafael Correa.

The negotiation process intensified with the appointment in December of a new Ecuadorean ambassador to the UK who had been instructed to concentrate on revoking the WikiLeaks founder’s diplomatic immunity.

Ecuadorean diplomats had expressed particular concerns over their country’s vulnerability to hacking by WikiLeaks if Mr Assange’s position were threatened, according to Whitehall officials with knowledge of the discussions.

The activist was effectively “in control” of the embassy, compromising the ambassador’s communications with his own government colleagues, officials said.

The final provocation came earlier this month when private photos of Mr Moreno’s family, dating back to his time living in Geneva, were circulated on social media. The Ecuadorean government has said it believes the pictures were shared by WikiLeaks.

With a bushy unkempt beard, Mr Assange appeared calm in court in London, dressed in a black jacket and black shirt, and holding a book by Gore Vidal. District judge Michael Snow said that Mr Assange’s decision to skip bail was “about as serious as it can get”.

The judge added: “His assertion that he has not had a fair hearing is laughable and is the behaviour of a narcissist . . . his behaviour is shameful.”

Mr Assange will also appear before Westminster Magistrates’ Court in May by video link in connection with his US extradition case, which will be heard at a later date.

Charges were not brought against Mr Assange during the Obama administration after officials concluded that there was no clear line between the publication of classified documents by WikiLeaks and the activities of US news organisations.

The stance changed after Donald Trump became president, despite his praise of WikiLeaks during the campaign, when it published hacked emails that were damaging to Hillary Clinton. In April 2017, Jeff Sessions, then US attorney-general, said Mr Assange’s arrest was a “priority” for the Trump administration.

Relations between the WikiLeaks founder and his host nation became strained after Mr Moreno’s election in 2017. The Ecuadorean embassy last year established new rules for Mr Assange, requiring him to pay his own medical bills and clean up after his cat.

In his video explaining the asylum decision, Mr Moreno cited “hostile and threatening declarations” against Ecuador by WikiLeaks.

He said this included a leak of confidential Vatican documents by WikiLeaks in January, and added that “key members” of WikiLeaks “visited Mr Assange before and after such illegal acts” and said this “confirmed the world’s suspicion that Mr Assange is still linked to WikiLeaks”.

Sajid Javid, UK home secretary, said on Twitter: “I would like to thank Ecuador for its co-operation and [the Metropolitan Police] for its professionalism. No one is above the law.”

Jeremy Hunt, UK foreign secretary, described Mr Moreno’s decision to terminate the WikiLeaks founder’s asylum as “courageous”.