When Gangu Chaudhary got a call to come to Kathmandu from his home in western Nepal, all he knew was that his 12-year-old daughter, Srijana, had fallen sick. He arrived at the family house where she had been working to be told that his daughter had doused herself in kerosene and then set herself alight, dying of her injuries shortly afterwards.

Srijana was a "kamlari", a domestic slave.

As bonded labourers working off debts, Srijana's family remains trapped in the quasi-feudal caste system still operating in parts of the country.

Since the 1950s, young girls from Nepal's Tharu community have been sold or given away by their families as a way of repaying debts to higher-caste families. Many face years of menial and unpaid domestic labour, violence and abuse. Chaudhary says that he was pressured by his landlord to hand over his daughter in exchange for some land. He never saw her again.

But now, two months after her body was cremated, Srijana's death could mark a turning point in Nepal's battle to end this ancient form of slavery. Last week, the government pledged to end the enslavement of all remaining kamlari girls by the end of the month, help to rehabilitate them once free, and prosecute the families that had enslaved them.

The government's decision followed a wave of protests and strikes, in the capital and across southern Nepal, over continued discrimination against kamlaris. The unrest was prompted by the refusal of the police to investigate Srijana's death, which was ruled suicide.

The Freed Kamlari Development Forum (FKDF), a kamlari rights group, says its own investigation into the case revealed numerous inconsistencies in the testimonies of witnesses.

"There are many examples of sexual abuse, rape, disappearance and unexplained deaths of kamlaris," said Fakala Tharu, a lawyer with the FKDF. "We are currently investigating a second case where a kamlari died of burns and three others where kamlaris apparently hung themselves."

Officially, all forms of bonded labour, including the kamlari system, have been banned in Nepal since 2000.

Yet campaigners believe that thousands of young girls like Srijana are still living as indentured slaves throughout the country.

"It is the powerful politicians from the upper castes who typically keep kamlaris, so they have no incentive to abolish the system," says Churna Chaudhary, the executive director of Backward Education Society, which has been campaigning for an end to all forms of bonded labour since 1985.

Last week, 10 activists were hospitalised and dozens arrested after police baton-charged an anti-slavery demonstration led by former kamlari slaves in Kathmandu.

Among the injured was Urmila Chaudhary, one of the leaders of protest.

Chaudharyhas first-hand knowledge of life as a kamlari slave. She was six when she was sold to a wealthy family and sent to work in Kathmandu.

"My childhood was very bad. I don't like to remember it," she says. "I was separated from my parents, my owners beat me, and when I was sick no one cared for me. They would give me rotten food, while their dog got fresh milk. My life was worth less than that dog."

Kamlari groups had called an indefinite strike across Nepal's southern districts, mobilising their network of activists to guard roadblocks, barring all transport from roads, and forcing businesses and schools to close, effectively bringing parts of the country a standstill.

Tharu said the government agreement was a milestone in the campaign to rid Nepal of child domestic slavery.

"I believe the government is now serious about this issue," said Tharu. "They have changed their attitude, but it would not have been possible without this protest."

Despite the government's poor record on implementing its promises, Shanta Chaudhary, a former MP and an ex-kamlari, remained cautiously optimistic.

"I worked as a kamlari from the age of eight and I've now been campaigning to end this practice for 18 years, so I am overjoyed that the government has finally committed to liberating and rehabilitating all kamlaris," she says. "The government must now fulfil its commitment. I believe it will, but, if it does not, we will come back to continue our campaign."

Churna Chaudhary added: "We have organised strikes, protested outside district headquarters, lobbied political parties, and even met with the president. You have to remember that these kamlaris are survivors. Think about the exploitation they have already experienced in their lives. They do not give up easily."