Sabah, Malaysia - Maslina Madsail dashes across the rickety wooden planks that link the floating huts of her water village whenever she hears that authorities are near.
"We run when we see the police truck coming. We run into the boats to hide," she said.
Quick-footed and nimble, Maslina looks smaller than her 11 years, but she has already learnt how to outsmart police intent on finding children like her.
From floating fishing villages to palm oil plantations, tens of thousands of children across Sabah state on the Malaysian island of Borneo are playing a dangerous game of cat and mouse with authorities.
Their crime? They are stateless - citizens of no country. Officially, they do not exist.
101 East - Sabah's invisible children
Estimated to number at least 50,000, according to non-governmental organisations such as the Asia Foundation, Sabah's hidden children are among the country's most vulnerable.
They are the offspring of migrant workers from the Philippines, Indonesia, or the nomadic sea tribe known as the Bajau Laut. By law, they are not allowed to marry or have children.
Many of these migrants work in Malaysia illegally. They form the backbone of Sabah's economy, working in industries such as palm oil plantations, construction, and fishing.
A Bajau Laut father teaches his children how to mend a net [Chan Tau Chou/Al Jazeera] 
In constant fear
Some families have lived in Malaysia for generations, but parents do not register births due to fear of arrest.
Denied access to public schools and healthcare, the children and their parents can be thrown into detention centres at any time and deported, even though Malaysia is often the only home the children have ever known.
"Authorities often conduct checks and the children live in constant fear," said Flora Yohanes, a teacher at a makeshift school run by a Malaysian NGO in Sabah. 
With public schools off-limits to undocumented children, many attend rudimentary schools run by NGOs.
About 80 students aged seven to 12, whose parents are Indonesian, attend the school where Yohanes works with three other teachers.
Indonesia and Malaysia have an informal agreement that the children will not be detained while they are in class, but they are at risk of arrest outside the school compound.
When the children hear that police are conducting checks, Yohanes said they often stay away from school for a week.
Makeshift school in Semporna for undocumented children who are denied access to public education [Chan Tau Chou/Al Jazeera]
"Sometimes there will only be teachers in the school, none of the students will attend," she said.
"When asked why, they say they were asked to hide. When they feel it is calm, they will start coming back to school. Sometimes, even while in school, they feel really scared ... that there are police patrols."
Yohanes said children often hide in the forest overnight to avoid police.
"When they are with their parents, they are no longer under the protection of the school. That's why they are told to run," she said.
Dying to stay out of jail
The children do not always escape.
"When the students get arrested, as teachers we are saddened," Yohanes said.
"Sometimes we can't sleep pondering the fate of the students, and trying to figure out how to help free the students from jail."
In some cases, the teachers are able to help get their students released. But some students are detained for more than three months before being deported.
Hunted down in a place they call home, an uncertain future faces the stateless children of Sabah [Chan Tau Chou/Al Jazeera]
Sometimes, children's attempts to evade authorities can be deadly.
In March, three teenage brothers died while hiding from police underneath a fish market in the town of Lahad Datu.
The boys' parents came to Sabah in the 1970s to escape civil war in the Philippines' Mindanao province. All of their 10 children were born in Malaysia.
Their mother, Erma Manding, is grief-stricken over the loss of three of her sons.
"It would be better if I died," she told Al Jazeera, sitting on the floor on their floating wooden home, surrounded by relatives.
Authorities say the boys had already drowned by the time they found them. But some locals told Al Jazeera that authorities sprayed toxic gas and suffocated the boys. Police have denied this claim.
Crime prevention?
Commander Abdul Rashid Harun, the head of the Eastern Sabah Security Command, said authorities conduct daily checks to track down undocumented migrants and their children.
Not allowed to step out of this palm oil estate for fear of arrest, undocumented children rely on discarded tyres and their imagination for a bit of fun [Chan Tau Chou/Al Jazeera]
Authorities sent home more than 18,000 undocumented migrants from Sabah last year.
"The illegal migrants are involved in many crimes, and smuggling is the number one problem. If we can stop the smugglers, we'll be able to stop related problems like kidnapping and armed intrusion," Commander Abdul Rashid said.
The command was set up in 2013 to beef up security in eastern Sabah after an attack by Sulu rebels from the southern Philippines.
Malaysian forces fought them off and since then, they've been cracking down harder on people without documents.
Locals often blame stateless children for a range of social ills.
"They're uneducated and many of them turn into drug addicts. Serious addicts. This is a big problem. And to feed their addiction, they steal and rob," said Lu, a fishmonger in the town of Tawau.
An undocumented life
Jerry Abbas, 37, knows what it's like to grow up stateless.
Undocumented children pick through garbage at a jetty in Semporna [Chan Tau Chou/Al Jazeera]
His father is Bajau and his mother Malaysian, but they never registered his birth. He said he found it impossible to find a secure job before he finally got his Malaysian passport five years ago.
"This document is my life," he said. "If I don't have the document, that is the end of my life."
Becoming legal opened the door for him to teach at a makeshift school run for Bajau children.
He said undocumented children often grow up in poverty and some resort to glue sniffing to stave off hunger.
"They are sniffing gum, begging on the streets, especially the young ones, and finding food in the garbage. That is the life of the Bajau Laut," he said. Here, the intoxicative inhalant is often referred to as gum.
In Semporna, on Sabah's east coast, children buy glue by the spoonful in plastic bags. Used bags litter the ground.
"They are very poor," said Abbas. "They don't have enough food to eat. By using glue, they can … sleep well."
Bajau Laut child in Kampung Halo, Semporna [Chan Tau Chou/Al Jazeera]
The prospects for stateless children may seem dim but some, like Maslina Madsail, have high hopes of clawing their way out of poverty and into mainstream society.
Maslina, who attends Abbas' school and lives in a small hut with 26 relatives, already works to help her family make ends meet, selling plastic bags to shoppers at a fish market.
She said she wants to be an immigration officer when she grows up so that she can give her family passports.
But in a country that does not even recognise her existence, that goal is likely to remain far beyond her reach.
For more on Sabah's Invisible Children, visit Al Jazeera's 101 East programme, @AJ101East
Follow Chan Tau Chou and Liz Gooch on Twitter: @tauism101, @liz_gooch 
Source: Al Jazeera
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