The NHS Direct service took over half a million enquiries over the 2006 Christmas period.

The phone helpline received over 250,000 calls in the 10 days to January 4, while the website had 340,000 visitors. Site visits were up 30 per cent compared with last year, while the number of telephone enquiries was 15 percent lower than last year.

However at the start of this week the NHS Direct website began having difficulties according to website performance monitoring company, Keynote. At just before midday on Monday 8 January, the site recorded low availability which carried on throughout a large proportion of the day; it was completely unavailable between 10pm and midnight.

The site's problems initially looked to have been rectified, however, between 7am on Tuesday until 1am on Wednesday the site was only available 28.6 per cent of the time.

The company said the site was still suffering problems well into Wednesday afternoon and visitors to the website were getting error messages and pages were very slow to load.

The company told Computeractive today the problem does seem to have been solved. But a spokesman said it was worrying that it had taken slow long to sort out.

Haran Sold, Keynote's managing director said: "The NHS Direct site is a vital tool for providing health advice to a wide range of people, created to take the pressure off other medical services.

"If the site is unavailable, or slow to perform, those people seeking instant reassurance about their own health, will be forced to go to other sources, putting pressures on the NHS Direct phone lines, GPs and hospitals.

"Websites providing services, especially ones as important as health have an obligation to provide high performance online."

NHS Direct has also recently been launched on the Freeview digital TV service, although statistics on its use are not yet available.