Repulse Bay tragedy: Matilda Hospital gave details of sisters' births to officials

The mystery behind two teenage sisters who were born and raised in Hong Kong with no official identity documents deepened last night as staff at a private hospital confirmed it had notified government authorities of their births in the mid-90s.

The case, believed to be unprecedented, has prompted the Immigration Department to consider a review of its processes so as to avoid another such case.

"We have to balance everything and see what we can do better," a government source said.

The case only came to light after the 15-year-old daughter of British insurance executive Nick Cousins, 58, and his partner Grace Garcia, 53, jumped to her death from the family's 19th-floor luxury flat in Repulse Bay in the early hours of Tuesday.

The couple's 14-year-old daughter was last night reunited with her father, who was released on bail, after spending a night in a Tuen Mun centre run by the Social Welfare Department.

Under the birth registration system, immigration officers send a letter by registered mail and telephone the parents if they fail to register their child's details within 42 days of their birth.

At least three or four reminders are sent to parents over the next few months if there is no response. No home visits are made.