The two mothers have been traumatized by the incident and are now receiving specialist counseling.

But even if the Queen Elizabeth Hospital staff scurried to confirm the identities of the babies after the mix-up was discovered on August 8, the two women carried on with breast-feeding the wrong babies until the mix-up was straightened out on August 12, the hospital chief executive Hung Chi-tim said.

Secretary for Food and Health York Chow Yat-ngok said he was "very concerned" about the incident. He has asked the authority to investigate and submit a report to the bureau.

"If there is any negligence or mistakes involved, the authority should explain to the public as soon as possible and take improvement measures to prevent a recurrence," Chow said.

Queen Elizabeth Hospital and the Hospital Authority also came under fire from the media for delaying the announcement of the blunder by a week.

However, the hospital explained they only wanted to protect the families' privacy, at their request. The hospital also reported the blunder to the Hospital Authority head office via the advanced incident reporting system on August 9.

Thomas Wong Hon-kwong, the hospital's chief of service, obstetrics and gynecology, said the blunder was due to "human errors" of staff at the postnatal ward and not a system flaw.

"The identification bands for the two babies were not applied immediately and individually," the hospital said last night. "The babies were put on the wrongly labeled cot from the incubators. The ward staff did not check the information on the wrist bracelet when applying the ankle band. Information on the wrist bracelet also was not verified with detail on the ankle band by ward staff of all shifts."

According to the hospital, the baby girl on bed No 25 who was born at 1.49am on August 7 was given an identification bracelet before she was sent to the postnatal room at 3am.

Another baby girl born 35 minutes later was put on bed No 10. She was also given a handwritten bracelet that contains her gender and the mother's name before being transferred to the postnatal room.

The babies were placed inside two separate temperature tanks to keep them warm before they were sent to their baby bassinets. Both babies were given their barcode anklets at around 5am.

On August 8, the mother of the baby on No 10 bed found the newborn was wearing a bracelet No 25. After being informed, the medical staff discovered the baby on No 25 bed was wearing both a No 10 and a No 25 anklet.

Babies' records including their weight and footprints were subsequently checked. Blood and DNA tests confirmed their identities on August 12. The babies were discharged with their correct mothers on August 13.

The hospital said measures were taken immediately after the incident: labor room staff will put the identification band on a baby's left foot instead of a bracelet on the left wrist; postnatal ward staff will put a two-dimensional barcode identification band on a baby's right foot.

An investigation team will come up with a report within four weeks.