A pioneering children's casualty unit can rarely open because of a staff shortage caused by the sheer number of patients at the accident and emergency department at Bradford Royal Infirmary.

The unit was built as part of £4 million development of A&E services in 2000 and includes a waiting area, play facilities and child friendly paediatric examination and treatment rooms.

But an audit of the department's opening times carried out by Bradford Teaching Hospitals NHS Trust shows that in the first three months of the year the department has been open only six days, between 1pm and 9pm - a total of 48 hours.

Now the final report of the city's health watchdog before its abolition in September has flagged up the problem as an area of concern and called for the situation to be closely monitored.

The report entitled "Achieving Change" says: "The A&E children's department is prone to staff shortages, often meaning that the facility has to be closed.

"This frequent closure means that no children's accident and emergency service is provided, with the situation worse than before the department opened."

The A&E department is the third busiest in the country, treating more than 105,000 patients each year, up to 25 per cent of which are children.

Jamil Rehman, chief officer at Bradford CHC, said it acknowledged the sheer numbers of people using the department was part of the problem.

"When the department is busy priority is given to the main department, meaning there isn't the staff to keep the children's department open.

"We keep mentioning this problem to the trust but at the moment there seems to be no answer. We are arguing that Bradford was in an unique position, with a model children's A&E, but it isn't functioning to its full capacity.

"If it needs more staff bringing in then that is what should be done. The CHC was heavily involved in setting up the department and we are keen to see it working properly."

A spokesman for Bradford Teaching Hospitals NHS Trust, said A&E facilities in Bradford were among some of the best in the country but a lack of resources meant that the children's department - which is supposed to be open each day between 1pm and 9pm - remained shut.

"We are working to obtain the resources in the near future to open the children's A&E department every day," said the spokesman.

"Until this time children will continue to receive high quality care and treatment in the main A&E department.

"From next month, we will be evaluating the situation as part of a wider ranging assessment into waiting times.

"This is part of the national Emergency Services Collaborative, which aims to evaluate waiting times and suggest improvements where necessary."

A&E consultant Tony Shenton said: "It would be unsafe a lot of the time to open the children's department because we would be stretching the availability of staff too thinly."