Julian Assange's father has today spoken out about his 'anguish' for his son who he claims could face 150 years in prison unless he agrees to a plea bargain.

Speaking from his home in Melbourne, John Shipton told Good Morning Britain he wants his son to return to Australia, 'for some fresh air and a chance to consider what he’s done.'

He claimed the WikiLeaks founder had spent a 'crushing' 18 months in isolation despite entertaining a host of high-profile celebrity guests during his seven-year stay at the Ecuadorian Embassy in London.

Assange is currently in Belmarsh high security prison following his dramatic arrest at the embassy a fortnight ago.

Julian Assange is currently in Belmarsh high security prison following his dramatic arrest two weeks ago (pictured)

Among Assange's callers at the embassy were actress Pamela Anderson, singer Lady GaGa, football star Eric Cantona and film directors Michael Moore and Oliver Stone.

Mr Shipton, who spent every Christmas at the embassy with his son, said he wants him to return home, 'for the sake of his health.'

He told ITV he 'felt anguish' for Assange when he saw footage of his dramatic arrest a fortnight ago.

He added: 'But I did notice that Julian had combed his hair, so he was still aware and in control of what he could control. But he hasn't weathered well after 18 months of isolation and no touch torture.

'I don't think it's anything to do with putting yourself in that terrible position. The cause – well, you guys are in the business, you would know that the cause has its nobility and there's many war crimes that Julian has exposed for you guys to publish and look at and examine.'

Mr Shipton has asked Australian Prime Minister Scott Morrison to bring his son home, arguing it was 'time for Australia to step up diplomatic efforts.'

John Shipton (pictured on GMB today) is appealing for his son's return to his home in Australia

Among Assange's callers at the embassy were actress Pamela Anderson, singer Lady GaGa, football star Eric Cantona and film directors Michael Moore and Oliver Stone

Assange, 47, has been holed up under asylum inside the embassy since 2012 when he was accused of sexual assault by two women in Sweden.

The Australian denied their claims but refused to travel to Sweden to face them, saying it was part of a ruse to extradite him to the US due to his involvement in the leaking of a huge amount of classified documents in 2010.

Those charges were dropped in May 2017, but Swedish prosecutors say they are now re-examining the case after a request by one of the alleged victim's lawyers.

The United States has also been trying extradite him over the leaks of classified documents through the Wikileaks website in 2010.

Mr Shipton added: 'The WikiLeaks library contains three million cables for the United States - an unsurpassed library of what shaped the 21st Century… how the geopolitical world is put together, composed and disposed - that is a considerable achievement.'

When asked about the sexual charges against his son, he said: 'Julian constantly offered from the minute that he was notified that there were allegations, to be interviewed.

'He went to England upon permission from the prosecutor. Instantly as he left, she issued a warrant.

'Julian sought protection from the embassy…he can no longer speak for himself so his family and friends must speak for him.'

Supporters of WikiLeaks founder Julian Assange are staging a protest outside the Supreme Court in London today

Supporters holding aloft banners reading 'Free Assange' in London this afternoon

Assange (pictured in 2017) sought asylum at the Ecuadorean embassy in London seven years ago to avoid extradition to Sweden over sexual assault charges levelled against him

On his son's extradition, he added: 'I imagine they will hold Julian incommunicado, they'll say to the public that Julian said this and that, whatever advances their position politically and legally, and they will do a plea bargain saying you will have 150 years in jail or 40 years if you plead guilty to some crime or another.

'But [I don't lose hope] in the slightest.

'I haven't had contact with Julian, communications are being set up - you can't ring people in Belmarsh maximum security.

'I believe that the last 18 months have been almost crushing, and it's good to see that ending.

'A good metaphor would be that if you're in a shipwreck you crawl up onto the beach and you're quite relieved to find yourself alive even if you're not quite sure where you are.'