The end of the cyclone season comes as a relief to most Rohingya in Bangladesh's Kutupalong refugee camp. But not Noor Alom, who had been searching for his six-year-old daughter for two days.

Fatima left their home, which sits near three putrid latrines, to play on a nearby hillside - and never came back.

"Nobody has any news about her," Alom told the Thomson Reuters Foundation after another exasperating search in the blistering heat, his wife rocking on the floor beside him.

"I am so worried that someone has sold her and taken her to another place," he said. "People told me that it occurs here."

His fears are not misplaced.

The United Nations said trafficking networks already exist in southern Bangladesh's sprawling camps, which have been overwhelmed by the arrival of more than 600,000 Rohingya fleeing Myanmar over the last two months.

It said killings, arson and rape of Rohingya Muslims by troops and ethnic Rakhine Buddhist mobs since Aug 25, in response to coordinated Rohingya insurgent attacks on security posts, amount to a campaign of ethnic cleansing.

Six out of ten of the new arrivals in the Bangladesh camps are children, providing a fertile hunting ground for traffickers looking for young girls to recruit as maids.

Thousands of children have, at some point, been separated from their families amid the chaos.

"It is a major, major risk," said Jean Lieby, head of child protection at the Unicef in Bangladesh.

"Young girls might enter into this type of trafficking and then end up in one of the big cities."

Kidnappers

Nazir Ahmed, a Rohingya refugee in the camp, set up an information centre two months ago, which he said has already reunited some 1,800 lost children with their parents.

Despite its important title, the centre's only equipment is a wooden table and a megaphone. But, from the moment the sun rises, it is inundated with people looking for their loved ones.

"For the Rohingya who have just come here, this place is new," said Ahmed.

"If they go far from their house, they can easily get lost."

On the morning the Thomson Reuters Foundation visited, two toddlers sat beside Ahmed, staring with terror at the wall of bodies in front of them.

"We are telling all brothers of the Rohingya, two children have been found and now they are with us," Ahmed announced over the megaphone, to the amusement of one child.

"If these children are yours, you can take them," he said, describing their red and yellow T-shirts, and how one had no pants on while the other had a toy in his hand.

"If they belong to your relative, you can inform them that they are here."

Ahmed does not disclose the children's names to protect them from potential traffickers. To claim a child, a parent must correctly recite their name and the child must confirm that the adult is their mother or father.

Ahmed is only too aware of the threat of human trafficking in Kutupalong. Only a day earlier, an unfamiliar man tried to snatch a child sitting on a footpath. He was swiftly attacked by the child's relative who was buying food from a nearby shop.

"We are telling all the people that there are kidnappers here, so be careful with your children," Ahmed said.

A few hours after the first announcement was made, only the child in the red T-shirt remained, clutching some tattered bank notes donated by a sympathetic member of the audience.

As Ahmed hung up his microphone, a woman forced her way behind the table. The child stretched his slight arms towards her and, for the first time that day, cried uncontrollably.

"I lost my child after he followed his father out of the house this morning," his mother, Diloara Begum, said after an emotional reunion.

"Some people told me the child will have died, others told me the child will have been kidnapped...When I heard he was at this place, I felt so happy I touched the sky with my hand."

Bonded labour

Trafficking is not the only form of exploitation that young Rohingya face in Bangladesh.

Other desperate families are selling their children into bonded labour, most commonly in the fish drying industry that dominates the nearest city, Cox's Bazar, Unicef said.

Families receive 18,000 taka (US$217) while their children work to pay off the debt during the nine-month fishing season.

To encourage parents to keep their children in school, Unicef has given more than 400 poor families who arrived in 2016 the same sum in cash, plus grants to start small businesses.

The agency would like to offer cash grants to the latest arrivals as well, but funding is tight as millions of dollars are also needed for essentials like water and medical care.

With the spectre of child trafficking looming large over the Rohingya camps, Alom was fortunate. After a three-day search, he found Fatima crying on one of Kutupalong's dusty streets.

"My heart and mind were broken, no one knew anything about her," he said. "Once I saw her I was so very happy, I don't care what happened or where she went, I am just so happy."