One day this summer, 11-year-old Ayu married 41-year-old Che Abdul Karim Che Hamid at a small pink mosque on the banks of the Golok river in the far south of Thailand. Earlier that morning, Che Abdul Karim and his soon-to-be child bride had travelled over the border from Malaysia into the Thai province of Narathiwat for the wedding. After a short ceremony at 11am and a trip to the Islamic Council offices to get their marriage certificate stamped, the couple crossed back over the border. Ayu was now Che Abdul Karim’s third wife.

In Malaysia, where men can legally marry girls under 18 if they get Islamic sharia court approval, Ayu’s case caused a national outcry in parliament and protests on the streets. But over the border in Thailand, where the controversial union took place, the response by the government and religious authorities has been notably muted.

Facebook Twitter Pinterest The mosque near Sungai Golok where 11-year-old Ayu married 41-year-old Che Abdul Karim.

Hashim Yusoff, the imam who married the couple, defended the arrangement: Ayu (not her real name) was “mature” he said, so the marriage was sah (legal under sharia law). The imam did make Che Abdul Karim – himself an imam in a rural village – pledge not to have sexual relations with his young wife, but medical tests since are said to show that the 41-year-old did not keep his promise.

Ayu’s father, Madroseh Romadsa, who was present at the wedding to give consent, said simply: “We have never done anything wrong. In Thailand, many people get married at early ages.”

Since 2003, under Thailand’s strict child protection laws, no one under 17 can marry, and sex with a minor is a prosecutable offence. However, in the southern provinces of Thailand – Narathiwat, Pattani and Yalla, which are majority Muslim – a legal loophole allows Muslim communities to apply Islamic law to family matters.

According to this law, there is no minimum age for marriage and, culturally, girls are deemed eligible as soon as they start menstruating. In this way, child marriage has continued as an unregulated norm and a solution to underage pregnancy and rape – with the Thai government appearing to turn a blind eye.

“Here, if a girl is not married by the time she is 16, it is already felt to be too late and that no one will want to marry her,” said Amal Lateh, who lives in Thailand’s Pattani province and was forced at 15 to marry a relative 10 years her senior.

Facebook Twitter Pinterest Mohammad Lazim arranges cross-border marriages for Malaysian men.

The legal loophole has also created what Thai children’s rights activist Anchana Heemmina described as the “big business of cross-border marriage” – Malaysian men crossing into southern Thailand to easily engage in underage or polygamous marriages for which getting approval in Malaysia would be impossible or a very lengthy process.

Mohammad Lazim runs one such business, helping arrange cross-border marriages for Malaysian men. He works with more than 50 bridegrooms a year, mainly wanting a second or third wife – but insists never with underage brides. He says that his business is tiny compared with some.

“People come from all over Malaysia to do this,” he said. “Business is booming: instead of applying to a sharia court in Malaysia and answering all their difficult questions – a process that takes sometimes a year – the shortcut is to come to Thailand. Here there is no law.”

The practice is also particularly lucrative for imams practising on the Thai side of the Golok river, who charge four times as much to conduct a marriage for a visiting Malaysian as they do for people from their own community. In Malaysia, Che Abdul Karim would have found it difficult or impossible to obtain permission to marry Ayu; in Thailand, he simply paid the imam 4,500 baht (£105), and it was done. He has since been fined 1,800 Ringgit (£340) in a sharia court in Malaysia after pleading guilty to polygamy and conducting the marriage without the court’s permission.

Wannakanok Pohitaedaoh was forced into a violent marriage when young and now runs Luk Riang, a children’s shelter in Narathiwat. She said: “The biggest problem with child marriage in Thailand is that nobody wants to talk about it – not the Islamic Council, not the imams and not the government. It has always been swept under the rug, and that’s where they want it to stay.”

Her opposition is deeply personal. Wannakanok, now 34, was just 13 when she was forced into marriage by her parents and says the experience “haunts my soul to this day”.

“When he asked me to have sexual intercourse, I wasn’t ready for it. I didn’t even know really what that meant, so I refused, and then he raped me,” she said, sobbing at the memory. “He was very violent and every time he wanted to have intercourse, he would use violence. We were living at home, and my parents would hear me screaming.

“And it was the same for so many of my friends. Many of my friends who were 12 or 13 had been married to men who were a lot older than them, maybe in their 30s or 40s. But the girls were young like me and didn’t want sex, so violence was very common. We had no idea about sex at that age.”

Most of her friends were pregnant by 14. She still regularly hears similar cases to hers and Ayu’s. One 13-year-old girl, Naa, had recently been staying at the Luk Riang shelter while her mother worked in Malaysia. “Her mother came to pick her up but soon after they married her to a 40-year-old as his second wife,” said Wannakanok. “The family was very poor so she was a financial burden: it was easier to marry her off.”

Facebook Twitter Pinterest Wannakanok Pohitaedaoh who was forced into a violent marriage at 13-years-old and now runs a shelter for children in Narathiwat.

There are no official figures on child marriages in Thailand but data from the human rights commissioner of Thailand shows that, in 2016 alone, in the public hospitals of Narathiwat, 1,100 married teenage girls gave birth. This does not include the three other provinces where child marriage is condoned, or births in private clinics and at home.

But the Thai government appears reluctant to engage with the problem at a senior level, pushing responsibility back to the provincial Islamic councils. “This issue has never been raised in the Thai parliament,” said Heemmina. “The government want to pretend it’s not happening because they don’t want to provoke the communities. They are protecting themselves.”

Their reluctance, she added, is rooted in sensitivity over self-determination for Islamic communities in the deep south of Thailand. For 14 years, a civil war has been raging in Narathiwat, Pattani, Yalla and occasionally southern areas of Songkhla. Its roots lie in Thailand’s annexation and conquest in 1909 of the Malay sultanate of Patani, which covered most of these provinces. A separatist movement formed in the 1950s exploded into all-out insurgency in 2004. Though the conflict has quietened in recent years, bombings and shootings are still common, and the fighting has cost almost 7,000 lives, 90% of them civilians.

A girl raped in her village was taken to a shelter, but the Islamic Council visited to try to make her marry her rapist

As a result, policies imposed on the south from Bangkok are often a great cause of friction. The Thai government, which has thousands of troops stationed across the south, has little interest in stirring up tensions further by interfering in an issue deemed religiously sensitive.

Suraporn Prommul, governor of Narathiwat province, said he had recently met with the Islamic Council over the issue. However, the only change Ayu’s case had prompted was an agreement that in future – in cases involving a young bride and a foreigner – the couple must go first to the provincial Islamic Council office to get married, so the committee can look closely into the case.” There was no stipulation on how this would be enforced.

After the furore in Malaysia over Ayu’s marriage, the girl and her family have this month returned to their native Thailand. Child rights activists fear the Thai government’s apathy over the issue means Che Abdul Karim, who remains in Malaysia, will never be charged with child grooming and abuse. “I am scared this will be another case of child marriage legitimising paedophilia that is swept under the carpet,” said Heemmina.

The impact on girls of marrying before the age of 18 is globally accepted as causing lasting emotional and physical damage, but also perpetuating the cycle of poverty. Girls in the southern Thai provinces are commonly taken out of school once they are married. Many find themselves divorced and with a child before they are even 18.

Facebook Twitter Pinterest Amal Lateh, pictured with her son Mushin, was forced at 15 to marry a relative ten years older.

But Safei Cheklah, the president of the Islamic Council of Narathiwat, while emphasising that council “guidelines” advise that under-18s should not be married, and admitting that it is “not suitable” – still vehemently defended the practice: “I have to speak based on Islamic principle, and according to Islam, the father can give permission for the girl to get married as long as she has achieved physical maturity.”

For the secretary of the Islamic Council, Abdul Razak Ali, whose own mother was just 13 when she married his 70-year-old father, allowing under-18s to marry was justified as a way to prevent “hideous” cases of adultery or illegitimacy. This also extended to forcing underage girls who are raped to marry their rapists.

Angkhana Neelapaijit, the human rights commissioner of Thailand, recounted a recent case of a 15-year-old who was raped in her village in the Yalla province. The girl was taken to a shelter but two days later the Islamic Council visited the girl to try to force her to marry her rapist. “They said it would be best for her,” said Angkhana.

Even charities seem wary of taking action. Aiyub Chena, vice-president of Nusantara, an Islamic NGO working with deprived children in southern Thailand, defended child marriage, because it protects girls from being stigmatised if they are caught with a man.

“Adultery is wrong and sinful according to Islam but if they banned child marriage, I am worried that would make adultery acceptable,” he said.

“You can change the law but that won’t change the society here. It will mean unmarried girls who get pregnant will be outcasts, and their children will not be accepted because they are illegitimate.”

Yet across the Islamic world there is a movement towards outlawing child marriage. Algeria, Oman, Bangladesh, Pakistan, Egypt, Morocco and Turkey have all set the minimum age for marriage at 18, and recently Indonesia prepared a presidential decree to close the legal loopholes that allow child marriage.

In a small village in Pattani’s Sai Buri district, women spoke about how common forced underage marriage still is in southern Thailand. They described figures known as “facilitators” who would come to the village on behalf of men who are looking for a young wife.

Amal Lateh, who was forced into marriage at 15, said: “When the facilitators come to the houses, they don’t ask the fathers directly – they will say things like, ‘Do you have any lambs or baby goats you are selling?’ Everyone understands what that means: it means they are looking for a virgin to marry. And then an arrangement will be made between the girl’s father and the facilitator. The girl has no say.”

Facebook Twitter Pinterest Suranya Litae and her son Afdon. At 15-years-old, she was forced to marry by her family to help pay for their family home. All photographs © Hannah Ellis-Petersen for the Observer

Suranya Litae was 15 when she was forced by her father to marry a man 16 years her senior in order to help her family out financially. She spoke of her anger that the law did not protect girls from the trauma of underage marriage.

“I did not want to be married. I cried so much, and I wanted so much to run away,” she said. “But my family needed the money from my dowry to build a house. At that time I felt so sad because getting married meant I had to abandon my studies.

Sadly, Suranya, stroked the head of her seven-year-old son, Afdon. “I dreamed of being teacher,” she said. “But that didn’t come true.”