For the last year, Sam* has seen his baby only in 15-second snatches.

The 28-year-old Australian citizen, who lives in Sydney, has never met his 18-month-old son, who has been trapped in China with Sam’s wife, Gulyar,* since she returned there while four months’ pregnant.

Gulyar is a Chinese citizen and, like Sam, a member of the persecuted Uighur ethnic minority.

She is one of three mothers who the Guardian can reveal are stuck in China with their Australian children due to Beijing’s sweeping crackdown on the Uighur, which has left at least one million Muslims in detention centres across the far-western region of Xinjiang.

Sam*, a 28-year-old Uighur Australian man whose wife and 18-month-old baby are detained in China. Photograph: Carly Earl/The Guardian

Gulyar has to report to police every week. It is not safe for her to call Sam, as Uighurs say they can be arrested for communication with people outside China, so she is limited to posting photos or videos, no longer than 15 seconds, on WeChat, the Chinese social networking app.

Sitting at a Sydney cafe, Sam pulls out his phone and and finds Gulyar has posted a new video.

He opens it, watches as his son, a big-cheeked toddler in a green and yellow romper, pulls himself up on a couch and smiles at his mother who chats to him from behind the camera. Sam saves it, hits the heart button underneath so that Gulyar knows he has seen it, and then, 10,000km away, Gulyar deletes the video.

Sam’s phone is full of these precious, fleeting, 15-second glimpses of the son he has never met.

“Everything is my favourite, whatever she puts up,” he says. But the videos are also a source of pain.

“I couldn’t hold him. I don’t even know how heavy he is. Maybe he doesn’t even know who I am,” Sam says.

Australian visa rejected

Gulyar and Sam married in Urumqi, the capital of Xinjiang, in 2016. They went on a honeymoon to the US and Turkey, where they discovered she was pregnant.

“I was so excited, but a bit nervous as well, it was a really good feeling,” Sam says.

Gulyar applied for a visa to come to Australia, but it was rejected. Very sick with her pregnancy, she decided to go back to China to be near her mother, while Sam returned to Australia and continued the visa application process. Shortly after she returned home, persecution of Uighurs in Xinjiang intensified. Gulyar’s passport was confiscated and Sam has been unable to get a visa to visit China.

When his son was six months old, Sam was on a train in Sydney when he got a message from a friend in China, telling him Gulyar had been taken into one of the notorious and secretive detention centres.

“I cried so much on the train, that feeling…” he trails off. “Even people on the train come to me and said, ‘what’s happened?’ and I can’t tell them.”

He didn’t hear from her for two weeks. Eventually, Sam learnt Gulyar had been detained by the Chinese authorities and later released because she was still breastfeeding.

That piece of paper saying 'Australian citizen' ... if you don’t have blue eyes and yellow hair it doesn’t really work Sam

Gulyar says the authorities told her that when their baby turned one she would be arrested again and their son put into a state-run orphanage and then adopted out to a Han Chinese family. Sam says it is only the fact that her family have been paying bribes to police totalling more than 60,000 RMB (AU$12,500) that has kept her out of the camps.

The Chinese embassy in Australia was repeatedly contacted for comment but did not reply to detailed questions from the Guardian.

Sam has repeatedly sought help from the Department of Foreign Affairs and Trade (Dfat) to bring his son to Australia. He was initially informed the Australian government could not help him until there was proof his son had Australian citizenship – something he is entitled to by descent.

The Department of Home Affairs has twice rejected the citizenship application. After an 11-month battle, Sam’s son was finally issued a citizenship certificate in February, after the Administrative Appeals Tribunal overturned the department’s decision.

“It’s been like pulling teeth every step of the way,” says Michael Bradley from Marque Lawyers in Sydney, which represents Sam. “It’s been horrendous.”

Now, Sam faces a battle to get a passport for his son and a visa for his wife, who will also need permission from the Chinese government to leave the country.

“So it’s not a simple matter and I don’t know what the answer to that will be,” Bradley says. But he believes that if the Australian government wanted to help, there is a lot it could do.

“Ministerial intervention can achieve anything in a matter of minutes. If you’re a French au pair for example, then anything can be achieved … Ministers have immense power and discretion to make things happen or not, but they simply haven’t been interested.”

The Greens spokesman for immigration and citizenship, Nick McKim, who has been advocating for Sam’s family for the past year, agrees.

“I still have grave fears for the safety of Sam’s child, who is now an Australian citizen. I want to see Marise Payne and Dfat do a lot more to help bring not only Sam’s child but also his wife to safety here in Australia,” he says.

“Given we’re consistently told by the government that they have a strong relationship with China, I do believe that there’s a lot more that we can do.”

Michael Bradley has been working pro-bono in Sam’s fight to have his son’s citizenship recognised so he can be brought to Australia. Photograph: Carly Earl/The Guardian

In a statement, a spokesperson for Dfat said it had made inquiries about a number of individuals with connections to the Uighur-Australian community, but would not comment on specific cases.

The toll on Sam has been huge. Suffering from depression, he was forced to quit his job as a truck driver and now drives for Uber part-time. The money he earns is just enough for him to get by.

“He is an absolute shell of a person compared to the guy I met 11 months ago,” says Sarah Smith, a refugee advocate. “He was this young, fit, healthy, tanned man, now he has lost 10kg, he looks unwell, he looks ghost-like.”

As well as the pain of separation and fear for his family’s safety, Sam has also lost faith in Australia.

“That piece of paper saying ‘Australian citizen’, in the end, if you don’t have blue eyes and yellow hair it doesn’t really work,” Sam says.

But he says he does, occasionally, permit himself to hope and when he does, he pictures a very particular scene.

“I’m in the airport, I bring flowers,” he says smiling. “After what I’ve been going through, I don’t care if I sleep outside, as long as my wife and my son are with me. I’m not really thinking about having a good life, a wonderful life, all I’m thinking is to stay with my son and wife.”

*Names have been changed