Police have reclassified as murder a wounding case in which a 40-year-old woman was assaulted with suspected corrosive fluid on June 28 in Sha Tin, following the woman's death today.

At about 8.42am on June 28, Police received a report that a 59-year-old man was having a dispute with his 40-year-old wife in a unit at Pai Tau Tsuen. He splashed some suspected corrosive fluid over her and she had severe head injuries.

The man also had some burns to his limbs, and their nine-year-old daughter had burns on her face and limbs. All three were sent to Prince of Wales Hospital and the woman was unconscious.

Police arrested the man for wounding on the same day and he appeared at Sha Tin Magistrates' Courts on June 30.

The woman was certified dead at 9.53am today. A post-mortem will be conducted to determine the cause of death. Police investigations are underway.