Chancellor Gordon Brown and his wife Sarah were last night at the bedside of their tiny baby daughter as she battled for life after suffering a brain haemorrhage.

The couple were facing every parents' nightmare as they waited anxiously at one of the country's top neo-natal units - the Simpson Memorial Maternity Pavilion at the Edinburgh Royal Infirmary - where 11-day-old Jennifer lies critically ill.

The condition of Jennifer, born seven weeks premature weighing only 2lbs 4oz, is said to have "deteriorated" over the last 24 hours.

Experts warned that a brain haemorrhage in such a tiny baby could prove fatal. If she survived she could be severely handicapped.

Jennifer was transferred to Edinburgh on Friday after doctors at the Forth Park Hospital in Kirkcaldy, Fife, where she was born, became concerned about the results of an ultrasound scan.

Mr and Mrs Brown, who married in August 2000, have remained with her ever since.

A brief statement yesterday issued on behalf of Mr and Mrs Brown, said: "Sadly, Jennifer's condition following her brain haemorrhage has deteriorated over the last 24 hours.

"Gordon and Sarah are with her and are grateful for the support and good wishes they are receiving at a difficult time."

No further details were released about Jennifer's treatment or her condition.

Tony Blair and his wife Cherie, on an official visit to the Indian sub-continent, were said to be keeping in close touch with developments.

"All their thoughts and prayers are with Gordon, Sarah and baby Jennifer," said the Prime Minister's official spokesman.

Scottish Tory party leader David McLetchie said: "It is at times like this that you realise what are the really important things in life."

Last night, Mrs Brown's mother, Pauline - who is divorced from Sarah's father Iain - left the hospital after spending an hour visiting.

Jennifer's illness will have come as a shattering blow to Mr and Mrs Brown, who have been on a rollercoaster of emotions since the premature birth of their daughter.

Mrs Brown, a 37-year-old public relations consultant, had left hospital only the day before the ultrasound scan showed the baby had suffered a cerebral haemorrhage.

The Chancellor - a man not given to public displays of emotion - has scarcely been able to contain his joy at becoming a father for the first time at the age of 50.

After Jennifer was delivered by Caesarean section, doctors were initially encouraged by her progress.

She was said to have been breathing independently and tolerating small amounts of food.

But it had still been expected that she would remain in hospital until next month.

Doctors said that a small haemorrhage in premature babies was not unusual.

But the deterioration in Jennifer's condition was likely to be due to either a huge haemorrhage or the development of hydrocephalus.

A massive haemorrhage, although relatively rare, could prove fatal because a tiny baby's body would be unable to take the strain.

Hydrocephalus is not considered a fatal condition but can have serious long-term consequences