LONDON, May 28 (Thomson Reuters Foundation) - When Susi, a single mother from the Philippines, left for a job in Qatar, she convinced herself it was a sacrifice worth making for her children at home.
For more than a year, Susi's sacrifice involved waking before dawn and working past midnight, cooking, cleaning and looking after a Qatari family. Once every two months, she was given a "day" off - in reality, it amounted to eight hours off.
Conditions deteriorated when Susi was brought to Britain by her boss. She was given no time off, forced to sleep in a storeroom which she shared with two other maids, and forbidden to leave her employer's house, even to go into the garden.
The ordeal continued until Susi, who requested anonymity, found her confiscated passport while cleaning one day, and escaped.
"I was prepared to do anything to provide for my children," Susi told staff from a London charity who later advised her.
Britain has been keen to present itself as a world leader in the fight against slavery, servitude and forced labour, and passed an anti-slavery law in March to help victims like Susi.
But critics say the law fails thousands of foreign domestic workers by imposing visa rules that tie them to their employer, making them vulnerable to abuse.
Tied visas have "unintentionally strengthened the hand of the slave master against the victim of slavery", according to a parliamentary committee scrutinising the Modern Slavery Bill.
The rules have also been compared by Human Rights Watch with "kafala", a contentious visa sponsorship system used by Gulf states, which the United Nations says is a source of labour abuse that must be abolished.
"There's a significant amount of information showing that these types of visa facilitate abuse and make it difficult for people to access redress," said Izza Leghtas, a researcher for Human Rights Watch.
"It's very difficult for them to come forward and contact the authorities when their biggest fear is being deported back to their home countries and not being able to support their families," she told the Thomson Reuters Foundation.
There are 53 million domestic workers worldwide, 83 percent of them women, the International Labour Organization says.
Between 15,000 and 16,000 of them are brought to Britain every year - often to work as live-in cleaners, cooks, nannies, chauffeurs and gardeners for the wealthy.
A further 200 are given visas each year to work in diplomatic households, according to the Home Office (interior ministry).
Many, like Susi, are exploited by employers who lock them up, pay them a pittance and subject them to physical abuse and sexual harassment, campaigners say.
It has been harder to escape this kind of treatment since the British government introduced tied visas in April 2012 in an attempt to limit immigration, critics say.
"The private household is an odd employment place. You don't need to have a licence. There are no checks. It's completely unregulated," said Kate Roberts, who works for Kalayaan, a charity campaigning to improve domestic workers' rights.
"When you rely on your employer for everything - your immigration status, your visa, your job, knowledge of your rights - then you're in a particularly vulnerable situation," she told the Thomson Reuters Foundation.
Under the previous system, domestic workers were allowed to change employer once they were settled in the UK. Now they no longer have the right to change employer, to bring dependants or to stay longer than six months.
If they leave, even to flee abusive conditions, they are in breach of immigration laws. For many domestic workers, the risk of becoming undocumented, coupled with the loss of income and a roof over their head is too much of a gamble to take.
"Some workers, unfortunately, make a miserable decision to endure seriously exploitative employment in order to send something home rather than nothing," Roberts said.
A spokesman for the Home Office said the abuse of any overseas domestic worker was unacceptable, adding that Britain's anti-slavery law included "protections" for workers who had been found to be trafficked such as leave to remain for six months.
"Victims of abuse should not be afraid to seek help - they will not be deported," the spokesman said in a statement.
Kalayaan, set up in 1987 by a group of domestic workers, operates out of a former school in affluent west London with its rows of elegant, wisteria-covered white houses.
In the three years since the visa rules changed, 590 workers registered with the charity, 184 of them on a tied visa. Most come from the Philippines, Indonesia, India, Thailand and Nepal.
Kalayaan said 14 percent of the workers on a tied visa reported physical abuse compared with nine percent of workers who entered Britain under a different visa.
Domestic workers on a tied visa were also more likely to report psychological abuse, being forbidden to go out unaccompanied, a lack of privacy and no time off.
"Having a system like this, that ties workers who are vulnerable by the nature of their work, to employers sets a very bad example and reduces its (Britain's) credibility," said HRW's Leghtas, noting that Britain has yet to sign an ILO convention concerning decent work for domestic workers.
The government has commissioned an independent review of visa arrangements for overseas domestic workers.
The review, which will examine whether there is evidence the tied visa has led to the trafficking or slavery of domestic workers, is expected to report back by the end of July.
Despite being identified by the authorities as a victim of trafficking, Susi was told to make arrangements to leave Britain, Kalayaan said.
Had she entered the UK before the tied overseas domestic worker visa was introduced, she might be working for another employer now, and able to send money home for her children, the charity said. (Editing by Ros Russell)