A north-south divide in swine flu diagnosis is revealed today, with different advice being given to patients suffering from symptoms of the condition, depending on where they live.

The Herald has discovered that while online assessments for England will usually direct those with just two symptoms of swine flu to receive a call back from an NHS Direct adviser, in Scotland the same patients will be advised that it is safe to manage the flu at home.

NHS assessments south of the border do not even require patients to have a high temperature, one of the key components of swine flu, to receive advice from NHS Direct. They need only report two or more of the swine flu symptoms - a cough, sore throat, headache, runny nose, limb or joint pain, fatigue, vomiting or diarrhoea.

By contrast, patients using self-help assessments operated by NHS Direct's Scottish equivalent, NHS 24, will be told they have flu and that it "is safe to manage the problem at home" if they have a high temperature of more than 38.3C, a headache, a sore throat, a runny nose and general aches and pains.

Users are told: "Most people with flu do not need to see a doctor, as flu is usually a self-limiting' infection. This means that the body normally fights off the infection without medical treatment. The symptoms of flu usually clear within 4-10 days."

Scottish patients are advised to call NHS 24 if, however, they have returned from an area where swine flu is active or they have been in contact with a confirmed case in the UK.

It also advises people to call if the symptoms get worse or have not cleared within 10 days, if new symptoms develop, if the fever lasts for four days or more or if they are concerned about a child or an elderly person.

However, when The Herald tested the English system yesterday just before the new National Flu Service was launched, it discovered that NHS Direct was advising patients in a "courtesy call" that due to demand, they would have to wait hours for official help - "up till midnight tonight".

And after 3pm yesterday when the National Flu Service went online, the website crashed and assessments were out of action for hours due to weight of demand.

Visitors to the site attempting to have their symptoms assessed online were met with a holding page, which displayed the message: "The service is currently very busy and cannot deal with your request at this time. Please try again in a little while."

By 5pm, the site was receiving 2600 hits per second, or 9.3 million hits per hour.

The accompanying "swine flu hotline", through which people can have their symptoms assessed over the telephone, is not thought to have suffered similar problems.

Those suffering from suspected swine flu - or a person acting on their behalf - can obtain a code, which can be exchanged for the anti-viral drugs Tamiflu or Relenza, if the symptoms they describe suggest that they have indeed caught the virus.

A spokesman for the Department of Health said: "We're working hard with our IT people to expand the capacity to meet demand."

The service is said to be staffed by more than 1500 call handlers, with the option open for the government to recruit 500 more. The initial 1500 were said to be capable of answering more than 200,000 calls a day, or more than one million calls a week.

Scottish Health Secretary Nicola Sturgeon said Scotland was not launching the National Flu Service because NHS 24 and GPs were continuing to manage the demands on the service.

She said: "We are keeping this situation under review and if demand grows over the next few months we have the ability to opt into the NPFS service at a later stage.

"A separate Scottish flu response service was set up on June 1 by NHS 24. The staffing in it has grown to keep pace with the growth in flu cases.

"At present, calls to the flu response service and NHS 24 of people who believe they have flu-like symptoms are averaging at around 2000 per day."

One Scottish pharmacy expert said she was "perplexed" by the differences in diagnosis.

"It sounds as if NHS Direct is taking a much more cautious approach than NHS 24," she said.