Caritas Medical Centre on Wednesday said it is investigating what led to an elderly patient choking to death after he was given a regular meal despite not being able to eat solid food.

The man, 75, who had a history of cognitive impairment and high blood pressure, was admitted at the end of last month suffering from abdominal bloating and constipation.

He was taken off food and given intravenous fluids instead, but after his condition improved doctors decided he could go back to his usual diet of pureed food, officials said.

"By March 3, his condition continued to improve, and the medical team determined that this patient could return to eating his usual food, so it was recorded in his medical records as 'DAT', which stands for 'diet as tolerated'," the hospital's chief executive, Gladys Kwan, told reporters.

"We believe that the nurse and doctor responsible had a communication issue, as the nurse mistakenly thought the instruction meant he could have a normal meal."

Kwan said a student nurse was instructed to feed and monitor the man after each bite. Although the patient initially managed to swallow and chew, he soon began to cough, prompting the student to alert the medical team.

The man was declared dead after resuscitation efforts, the hospital said.

It added that it has apologised to the man's family.

Raymond Cheung, chief manager for patient safety and risk management at the Hospital Authority, said a committee has been established to investigate the incident and to implement improvement measures within eight weeks.