The rights of foreign workers in Saudi Arabia are being abused not only by employers but by the country's legal system, an advocacy group has claimed.
Foreigners work in many Saudi industries, from oil to health
A report by Human Rights Watch decries what it calls the failure of the Saudi justice system to provide redress.
It speaks of workers who face torture, forced confessions and unfair trials when they are accused of crimes.
But the Saudi embassy in Washington said the report "grossly exaggerates" a few instances of abuse.
"The kingdom... takes the issue of human rights very seriously and we continue to make progress in this regard," it said in a statement.
The 135-page report by the New-York based group catalogues abuses it says are suffered by a predominantly Asian labour force that makes up more than one third of the kingdom's population.
"Migrant workers in the purportedly modern society that the kingdom has become continue to suffer extreme forms of labour exploitation that sometimes rise to slavery-like conditions," it says.
It describes the case of 300 women from India, Sri Lanka and the Philippines who cleaned hospitals in the country's second city, Jeddah.
They worked 12-hour shifts, six days a week, and at night were locked in crowded dormitory-style accommodation where 14 women shared one small room.
Human Rights Watch says abuses on women are particularly disturbing.
"Some women workers that we interviewed were still traumatised from rape and sexual abuse at the hands of Saudi male employers," the report says.
The watchdog also recorded executions of foreign workers whose families only learned of the death sentence after it had been carried out.
Saudi Arabia's labour minister recently said there were between eight and nine million foreign workers in the country - a much higher figure than previous estimates.
Most are from the Indian subcontinent and South-East Asia.
While Human Rights Watch focuses on what it considers the pressing need for judicial reform, the International Crisis Group (ICG) urges the country's ruling princes to make a much stronger commitment to political reform.
Faced with a string of attacks over the last year by radical Islamists, the government, it says, has been tempted to cling to the political status quo.
The ICG report calls that a self-defeating strategy.
The government needs to repair its legitimacy, which the report argues has been badly battered by the closed and arbitrary nature of the political system, the concentration of wealth and power in the hands of the ruling family, and the corruption and profligacy of many of its members.