The United Kingdom on Friday approved the extradition of WikiLeaks founder Julian Assange to the United States for him to face charges for allegedly leaking classified documents.

UK Home Secretary Priti Patel approved the extradition. However, Assange can challenge the decisions of both the home secretary and the district court that approved his extradition, the Home Office said in a statement.

Assange can appeal against the decision within 14 days, a spokesperson said. WikiLeaks has said it would file an appeal, reported the Associated Press.

Assange faces 18 charges in the US in connection with releasing five lakh secret files on American military campaigns in Afghanistan and Iraq. The files were made public between 2010 and 2011. Assange is also accused of soliciting and publishing such information.

In April 2021, a British court had held that the 50-year-old could not be extradited to the US, as doing so would be “oppressive by reason of mental harm”.

However, in March, the country’s Supreme Court had ruled that there were no legal questions in connection with assurances given by the US about how he would be treated, according to The Guardian.

His extradition was formally approved in April by a district court. The case then went to the home secretary, who approved the extradition on Friday.

“The UK courts have not found that it [the extradition] 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.”

Meanwhile, Amnesty International Secretary General Agnes Callamard said that extraditing Assange send a “chilling message to journalists” all over the world.

“If the extradition proceeds, Amnesty International is extremely concerned that Assange faces a high risk of prolonged solitary confinement, which would violate the prohibition on torture or other ill treatment,” she said. “Diplomatic assurances provided by the US that Assange will not be kept in solitary confinement cannot be taken on face value given previous history.”

Stella Assange, the wife of the WikiLeaks founder, said the decision was not the end of the fight but a “the beginning of a new legal battle”, according to AP. She described UK’s decision as a “dark day for press freedom and for British democracy”.

Assange has been in UK’s Belmarsh Prison since April 2019, after he was removed from the Ecuadorian embassy in London.

American prosecutors have argued that Assange unlawfully helped US Army intelligence analyst Chelsea Manning to steal classified military files that WikiLeaks later published. They said Assange’s actions put many lives at risk.

Supporters and lawyers for Assange have argued that he was a journalist and is entitled to the First Amendment (freedom of speech) of the US Constitution for publishing documents that exposed US’ military wrongdoings. They argued that the case is politically motivated.