Rohingya women who fled their homes in Burma are now being beaten and abandoned by their husbands, while young girls are facing increased pressure to marry, aid workers say.
Polygamy, violence against women and forced early marriages are a "growing critical problem" in the cramped refugee camps in Cox's Bazar, southern Bangladesh, ActionAid is warning.
Almost 700,000 Rohingya refugees have fled neighbouring Burma since last August amid reports of extreme violence, forming a total of more than 900,000 displaced people in the numerous sprawling camps.
Many are already traumatised, and now face the potentially catastrophic disruption of the looming monsoon season, which charities fear will increase their vulnerability.
Rahima, who has four children under the age of 11, including a baby born in the camps, said her violent husband had abused her in Burma and continued to do so after they fled.
The 28-year-old had saved the equivalent of £3,500 and gold, which her husband stole before abandoning her and crossing to Bangladesh alone.
When she finally arrived in the camps with her children in September, she could not find her husband, later discovering he had remarried. He now plans to leave the camps with his new wife.
Speaking through a translator, she said: "Now I am saying to my husband: 'You may not think about me, I am your wife, but how can you ignore your children? They need food, they need materials to build their life, but he doesn't pay anything."
ActionAid is using British donations to run two women-friendly spaces and a centre in the Moinerghona settlement - safe havens where women and girls can socialise over games, take part in drama workshops, get health checks and, crucially, speak to trained counsellors to process the trauma they are carrying.
The charity has also set up Rohingya women-led committees to let aid workers know what they need to feel safe, such as separate, secure bathrooms, and solar lights to guide their way at night.
Almost 200 women have already received tailoring training using sewing machines and a further 180 are learning the skill.
Rahima, one of those trained, said she comes to the "peaceful" space almost every day with her baby to escape the crippling heat of her shelter and relax.
She is able to earn a little money from her machine embroidery, and wants to learn how to make fishing nets and caps.
But, she said: "I cannot think of hopes and dreams, because I already struggle with my four children. I can't see anything in my future. The future is dark, I don't see anything."
"I am depending on Allah because Allah helped to make my life rich for all these years so he will make sure that I will survive," she added.
Another Rohingya woman said her pregnant older sister had returned to sleep in the family tent because her husband, who she married in the camps, was physically abusing her.
The teenager said the family were worried about giving him the full dowry payment while he is being violent and fear he may seek out a second wife.
When the family became aware of the husband's actions they asked her to abort the baby, but she refused, and are now worried about her bringing up a newborn in such instability.
Women's rights and protection coordinator for ActionAid in Cox's Bazar, Shahanoor Akter Chowdhury, said intimate partner violence was "very common" and polygamy another "growing critical problem", with mothers desperate to secure their daughters' futures and men being bribed to remarry with the lure of large dowry payments.
But young girls spoken to by the Press Association said they were determined not to marry until they were able to return to Burma, where the dowry would be less.
She said: "The women who talked to us today - four months ago we wouldn't bring one word out of their mouth. Now they can talk about themselves, they can talk about their problems, their needs, they ask for solutions, they want justice. So they can cry for their demands and I see that as a very positive change."
Mike Noyes, deputy director of humanitarian policy and practice at ActionAid UK, who has recently returned from the camps, said they were focusing on putting women and girls in control.
He said: "At ActionAid we know from experience that in a humanitarian crisis, women and girls are hit hardest - and the situation of the Rohingya refugees is a particularly cruel example of this.
"Many of the Rohingya women and girls we're working with have suffered appalling sexual violence, and are deeply traumatised.
"On top of this, extreme poverty and desperation - such as we're seeing in Cox's Bazar - increases the risk of domestic violence, and puts pressure on families to 'marry off' their daughters or sisters to someone who can provide for them."