Millions slave without rights

It said that at least 52.6 million worldwide form an invisible workforce employed by the wealthy in roles such as maids, cleaners and carers beyond the reach of law.

Nine in 10 had limited legal protection as labour laws did not extend to their roles, while three in 10 had no rights at all.

The true total is likely to be far higher as many are not even counted in the official labour statistics on which the ILO study was based.

Around 83 per cent of known domestic servants are women.

The study excluded millions more aged under 15, who were thought to number 7.4m by researchers conducting the last major study in 2008.

Revealing its findings the ILO said many such workers were in a dire position.

The organisation's deputy general secretary Sandra Polaski said: "Domestic workers are frequently expected to work longer hours than other workers, and in many countries do not have the same rights to weekly rest that are enjoyed by other workers.

"Combined with the lack of rights, the extreme dependency on an employer and the isolated and unprotected nature of domestic work can render them vulnerable to exploitation and abuse."

The ILO called on governments to act to bring in and enforce minimum wage legislation and to extend labour rights to domestic workers.