When Brisbane man Hazem Hamouda landed in Egypt for a dream holiday with his Australian-born family, he never imagined it would land him in prison.

The father of six was whisked away by Egyptian security minutes after touching down.

More than a year later, Hamouda, 55, still languishes in a Cairo jail, where his mental and physical health are rapidly deteriorating.

Egyptian authorities accuse him of being associated with the banned Muslim Brotherhood and spreading false information – but no charges have been laid.

Hamouda’s eldest daughter, Lamisse Hamouda, 29, says her dad, who was an IT consultant with Queensland Health before flying to Egypt, has nothing to do with the blacklisted organisation.

“Spreading false news covers everything from social media activity to being a television presenter to being a comedian or university student who might have handed out a flyer – it’s a very broad accusation,” she said.

Little information has been provided to Hamouda’s family, who speculate the accusations may be linked to Facebook posts he made during the Arab Spring in 2011.

“There’s no formal evidence and we’ve been trying to rack our brains why they took dad, that’s the only possibility we can come up with, but even then it’s not really a reason to arrest someone,” she said.

Hazem Hamouda with his daughter Lamisse who says he has broken down during family visits to the jail. Photograph: Lamisse Hamouda

Hamouda, a dual Australian-Egyptian national, landed in Cairo on the anniversary of the Egyptian revolution, 25 January, when there was heightened security.

“The initial advice was ‘your dad will be out in six months, it’s just something they do, they round up people at this time and when they realise he’s done nothing they’ll release him’.”

That didn’t happen. Despite hard work by the Australian government and the family’s legal team, Hamouda remains locked in 9m by 3m cell with 13 other men in the notorious Tora prison.

“They share one squat toilet dad says has never been cleaned, and all sleep on the floor because there’s no beds,” Lamisse Hamouda said.

“Dad hasn’t lived in Egypt for 30 years. He’s putting on a brave face but he’s broken down quite a few times when we visit.”

A Hamouda family photo from last Christmas, without their dad. Mum (Evelyn), Amira (21), Lamisse (29), Jasmine (27), Harun (20), Kareem (14) and Saja (23). Photograph: Lamisse Hamouda

The family is also worried requests for him to see a surgeon outside the prison are constantly rejected.

They have started a Change.org petition saying they don’t want to wait anymore. “We want the Australian authorities to do more to help us find a resolution for our father and to bring him home.”

The Australian journalist Peter Greste echoes the family’s concerns. Greste spent 400 days in Tora prison following similar accusations – broadcasting false news and supporting the Muslim Brotherhood.

“It’s pretty grim, there’s very little time spent outside the cell … [and] when you’ve been locked up with no clear charges, and no clear end to it all, it’s very, very tough,” he said. “The Australian government certainly needs to be much more publicly involved.”