Between three and five foreign domestic workers in Hong Kong seek help each month from labor unions after their employers ordered them to work in mainland China.

Maesaroh, chairman of the Association of Indonesian Migrant Workers in Hong Kong, said most of the cases it received involved local employers who had houses on the mainland or couples working across the border, Apple Daily reported.

Eman Villanueva, vice-chairman of the Filipino Migrant Workers’ Union, said many domestic workers were afraid of being fired if they refused their employers’ requests.

Siti, an Indonesian maid, said her friend had been fired due to her refusal to go to work on the mainland.

Jugen, a Filipino maid who has worked in Hong Kong for a year, said her friend was made to go across the border to clean two big houses. She not only worked overtime but was not allowed to go out and lacked adequate food.

Her friend quit and went back to the Philippines.

The investigative reports were part of a series published by Apple Daily on Sunday about how domestic workers have been forced to work illegally in mainland China.

According to the reports, there now are about 200,000 maids working illegally in mainland China as the demand for skilled maids in big cities has increased.

Reporters discovered many domestic workers from the Philippines, Indonesia, Myanmar and Bangladesh gathered in the luxury residential areas of Tianbei district of Shenzhen. Most were seen in the afternoons picking up children from schools or going to markets.

May, an Indonesian maid who speaks little Mandarin, at first told a reporter that she had married a Chinese man and moved to Shenzhen, but she later admitted that she had worked in that border city for one year to take care of an elderly person for a monthly salary of 4,500 yuan (US$677), compared with the minimum wage of HK$4,310 (US$552) in Hong Kong.

May had only a travel visa, so she said she was extra cautious when she  went out because she knew she was an illegal worker.

Maesaroh reminded all maids that it is illegal to work in a location other than the one stated in their employment contract, adding that the Hong Kong government should prosecute employers who made such requests.

Read: Filipino maid forced to work 20 hours a day in Shenzhen