The schoolboy survived on the limited food his sister had left. He had starved for a few days until a social worker became suspicious after seeing him spend most of his days at a youth centre nearby.

The chronically ill mother expressed remorse and guilt over the abuse yesterday through her lawyer, in mitigation. She had left Thailand alone when she was young to marry in Hong Kong and thus had a small social circle, the court heard.

According to her lawyer, her marriage ended, and as she suffered financial difficulty and later health problems, she became suicidal and needed care from her daughter as she did not have the physical strength to look after her children.

But she promised to work with social workers to start anew, and reports had shown improvement since the incident. The mother and her children were now living happily together, the court heard.

Magistrate Bernadette Woo Huey Fang, of Fanling Court, issued the order yesterday after accepting a probation report that indicated positive progress in Tsang's household since she had initially admitted the offence in November.

The magistrate praised the mother's effort and hard work for the improvement seen in her reports.

She also advised Tsang to let a social worker, rather than the daughter, handle their family's welfare payout.

In a flat where electricity and water services had been cut off since June, the boy had to light candles at night and had not bathed or brushed his teeth during the week.