Sir Richard Branson is to launch a company which will let families bank and store stem cells from their child's umbilical cord.

Some believe the cells may be used in the future to treat conditions such as Parkinson's disease and cancer.

It is thought a few thousand couples have already used stem-cell storage.

The service is sometimes promoted to parents through leaflets provided in GPs surgeries and antenatal clinics and also in pregnancy magazines.

Parents can be provided with collection kits which are then taken for processing and storage but some companies send someone to collect the blood.

Virgin says its service is unique because it will offer a charitable element, allowing the NHS to use some of stem cells the company stores.

Sir Richard said "We will take a parent's individual cord blood and we will divide it in two.

"So, part of it will go into a national blood centre that anybody can get access to. And the other half will be put aside for the child."

He said this should help particularly high risk ethnic groups who are prone to conditions that can be treated with stem cells but who may have difficulty finding well-matched cord blood.

A report from the RCOG published last year advised doctors and midwives not to take part in the blood collection as they needed to focus on the welfare of the mother and baby.

They pointed out that the NHS collects up to 2,000 cord blood samples every year for storage in a public bank that can be used by anyone who needs a cord blood cell transplant, thera are currently 7,000 donations held.

Cord blood storage is also carried out in families at high risk of a condition - such as Fanconi anaemia - which could be treated with a transplant.

Sue Jacob, from the Royal College of Midwives, said the majority of maternity units did not have a policy for dealing with the collection of cord blood, putting midwives in a difficult position.