The surrogate mother was believed to be oldest woman to have given birth in Japan.

Surrogate births are extremely rare in Japan, and the Suwa Maternity Clinic in Nagano, north west of Tokyo, refused to provide information such as the date of the birth or sex of the baby. News reports said the baby was born last year.

"Both surrogate mother and baby were fine," said Chihiro Netsu, a spokeswoman for the clinic.

Ms Netsu said the woman was believed to be the oldest surrogate mother in Japan, and reports said she was the oldest woman to have given birth overall.

Japan's Health Ministry does not release precise statistics on mothers' ages, saying only that there were two births to women aged 55 or older in 2006, the latest year that figures were available for.

The surrogate mother used a fertilised egg donated by her daughter, who has no uterus, Ms Netsu said.

Mainichi newspaper reported that the previous oldest mothers in Japan were two 60-year-old women implanted with their own fertilised eggs in the US.

Japan Society of Obstetrics and Gynaecology, a powerful body with more than 15,000 members, has banned such procedures, but they are not illegal and individual clinics are free to perform them - though few actually do.

At Suwa Maternity Clinic, eight surrogate mothers have given birth. Of them, four women have delivered babies using fertilised eggs from their daughters.

The clinic will report the latest case at a conference of the Japan Society of Fertilisation and Implantation later this month.

It was the first time the fertilisation conference had taken up the subject of surrogate births, Ms Netsu said.