Britain's government on Friday approved the extradition to the United States of WikiLeaks founder Julian Assange to face trial over the publication of secret files relating to the Iraq and Afghanistan wars.
Home Secretary Priti Patel's interior ministry said Assange had 14 days to appeal the decision, which comes after a UK court issued a formal order clearing his removal.
Assange's supporters have held frequent rallies to protest the planned deportation.
His wife, Stella, has pleaded for his release from custody after they had two children in secret while the 50-year-old campaigner was holed up for years in Ecuador's London embassy.
WikiLeaks called Patel's decision a "dark day for press freedom and for British democracy" and vowed to pursue the appeal to the High Court, accusing the United States of having "plotted his assassination".
"Julian did nothing wrong. He has committed no crime and is not a criminal. He is a journalist and a publisher, and he is being punished for doing his job," the group said in a statement.
WikiLeaks said the case was "political", as Assange published evidence that the United States "committed war crimes and covered them up".
The extradition was an attempt to "try to disappear him into the darkest recesses of their prison system for the rest of his life to deter others from holding governments to account".
A Home Office spokesperson said there were no grounds for Patel to block the order.
"In this case, the UK courts have not found that it would be oppressive, unjust or an abuse of process to extradite Mr Assange," the spokesperson said.
"Nor have they found that extradition would be incompatible with his human rights, including his right to a fair trial and to freedom of expression, and that whilst in the US he will be treated appropriately, including in relation to his health."
Assange has become a cause celebre for media freedom, with his supporters accusing Washington of trying to muzzle reporting of legitimate security concerns.
He is wanted to face trial for violating the US Espionage Act by publishing military and diplomatic files in 2010, and could face up to 175 years in jail if found guilty, although the exact sentence is difficult to estimate.
He has been held on remand at a top-security jail in southeast London since 2019 for jumping bail in a previous case accusing him of sexual assault in Sweden.
That case was dropped but he was not released from prison after serving time for breaching bail on the grounds he was a flight risk in the US extradition case.
Assange, who married in jail in March, spent seven years at Ecuador's embassy in London to avoid being removed to Sweden.
He was arrested when the government changed in Quito and his diplomatic protection was removed. (AFP)