Domestic helpers in Hong Kong marched in protest Sunday after several maids fell to their death from tower block windows as they tried to clean them.

There are 300,000 maids in Hong Kong, mostly from the Philippines and Indonesia, with concern growing among rights groups over their welfare following several abuse cases.

A 35-year-old Filipina domestic helper fell to her death last month as she was reportedly cleaning the outside of the windows of her employer's flat.

Organisers of Sunday's rally said they believed at least three maids had died falling from windows this year.

Hundreds of helpers marched in the centre of Hong Kong Sunday shouting ‘We are workers, not slaves!’

In a city of skyscrapers, they are calling on the government to ban employers from asking maids to clean the outside of windows.

‘For us it's hard to say no when employers ask us to clean windows, but it's scary,’ said Dolores Balladares, a spokeswoman for the Asian Migrants' Coordinating Body.

‘It's about time for the government to protect the workers.’

Thai domestic worker Waen Takruerat, 42, said the majority of maids were expected to clean windows inside and out.

‘It's scary and dangerous so I told my boss I can't do it,’ she told AFP.

The plight of maids in Hong Kong was thrown into the spotlight by the case of Indonesian helper Erwiana Sulistyaningsih, who was beaten and starved by her employer Law Wan-tung in a case that made world headlines.

Law was jailed in February 2015 for six years.

Campaigners have long sought reforms, including ending the requirement for maids to live with their employers. They say this makes it difficult for them to escape abuse.

They also want the government to abolish the ‘two-week rule’ under which domestic workers must leave Hong Kong 14 days after they quit a job, unless they can find other employment within that time.

So far the government has shown no indication it will relax either rule.