One of 27 former foster home workers charged with child abuse on Thursday pleaded guilty to assaulting a two-year-old boy under her care.

The Kowloon City Magistracy heard that Heung Wing-shan, 46, who was a senior childcare worker at the Children's Residential Home in Prince Edward, grabbed the boy's hair and pulled his limbs last November and pushed his head against the toilet wall forcefully a month later.

Heung's lawyer said in mitigation that in the first incident, she was trying to stop the boy from hurting another child, and in the later case she was trying to focus his attention when using the toilet.

He added she expressed regret over what happened and was willing to apologise to the boy and his family.

The lawyer also said Heung suffered from anxiety and depression afterwards.

The court will hand down a sentence on June 22 after reviewing reports of the defendant's background and the suitability of imposing a community service order.

Nine other defendants who appeared in court on Thursday had their cases postponed to July 8 or August 4.

The remaining 17 defendants were due to appear in court on June 23, with prosecutors planning to transfer the cases to the District Court.

40 children were allegedly abused at the facility run by the Society for the Protection of Children. The incident came to light late last year after a complaint filed by a nearby resident.