WikiLeaks founder Julian Assange will take his fight against extradition to the Old Bailey on Monday.

The 49-year-old, who has been held in custody at high-security Belmarsh Prison for 16 months, is wanted in the United States over “one of the largest compromises of classified information” in its history.

He faces 18 charges, including plotting to hack computers and conspiring to obtain and disclose national defence information.

Allegations include that Assange conspired with army intelligence analyst Chelsea Manning to crack a password to a classified US Department of Defence computer.

If convicted, he faces a maximum possible penalty of 175 years in jail.

Assange’s supporters have accused the US administration of targeting the Australian national for “political” reasons after WikiLeaks exposed alleged war crimes and human rights abuses.

Last month, his partner Stella Moris launched a Crowdjustice campaign to help fund his defence which has now topped £100,000.

Speaking on Sunday, Ms Moris, who has two young sons with Assange, described the possible impact on their family.

She said: “To the boys, Julian has become a voice on the telephone, not their father whom they can see and hug.

“It is heartbreaking to think that if Julian is extradited and put in a US super-max prison, the boys will never get to know their father and he will never see them grow up.

“That is what is at stake for us as a family. But there are also much bigger issues that we are fighting for.

“Julian’s case has huge repercussions for freedom of expression and freedom of the press. This is an attack on journalism.

“If he is extradited to the US for publishing inconvenient truths about the wars in Iraq and Afghanistan then it will set a precedent and any British journalist or publisher could also be extradited in the future.”

The extradition case, which was delayed due to the coronavirus pandemic, is being heard by District Judge Vanessa Baraitser at the Old Bailey.

It is expected that dozens of witnesses will be called to give evidence over four weeks.

Assange’s legal team is being spearheaded by Edward Fitzgerald QC, with James Lewis QC acting for the US authorities.

Speaking ahead of the hearing, John Rees, of the Don’t Extradite Assange Campaign, said: “This is the press freedom case of the 21st century.

“Anyone who cares about freedom of speech, about the ability of journalists to tell the public what the powerful would prefer to remain hidden, should make their way to the Old Bailey and let their voice be heard.”