Symptoms:

According to the answer from the Department of Work and Pensions (DWP), the numbers of people claiming either Disability Living Allowance or Incapacity Benefit on these grounds have risen by 78 per cent and 25 per cent respectively since 1997.

The Conservative Shadow Work and Pensions Minister, Oliver Heald, said that the figures were a "worrying indicator" of the state of mental health in Britain. "They show what a priority improving mental health should be for our society," he said.

However, whilst the figures are a strong indicator of the social and economic cost of mental illness, not all mentally ill people get equal access to benefits.

Rethink, the mental health charity, says that the benefits system is complicated, with regulations changing frequently, so that "most families need expert help and advice if they are to receive their full entitlements".

The mentally ill also face additional barriers in filling out their forms, and DWP staff, the charity says, "often have little experience of mental health problems, so it is important for each answer to be given carefully and with sufficient detail". This is something which can pose great difficulties to a person suffering from a serious mental health problem such as chronic schizophrenia - where coherent communication is often a problem - or with active psychotic symptoms where answers to questions may be confused or bizarre.

One group of sufferers who face particular problems of their own when it comes to getting entitlements are those who suffer from agoraphobia.

Agoraphobia is the most common form of phobia, "constituting 60 per cent of phobias examined" (Davison and Neale). NHS Direct estimates that approximately five per cent of adults develop agoraphobia - although extremes of behaviour and its impact on quality of life can vary widely. The disorder typically begins during the late teens or twenties. Although more women are affected than men, experts believe that this may be because women are more likely to report their symptoms.

Taken from the Greek word for "marketplace", agoraphobics suffer from an irrational, but terrifying, fear of public and open spaces. This fear can vary from an irrational hatred of public places such as libraries, parks and shops - or crowds in general - to those who cannot even set foot outside their front doors and step into their own back gardens.

The resulting social exclusion suffered can be immense. In one case outlined in parliament by Dr Brian Iddon MP, a woman constituent suffering from agoraphobia lost her benefit and was forced to live on £29 a month. "She was expected to attend an interview tomorrow with respect to going to work. This morning, I have discovered, through examining her medical record with the practice concerned, that the medical evidence has not been considered with any seriousness, which has been very disturbing for her."

Dr Iddon appealed for the minister responsible to ensure that all benefits staff "treat people with mental illnesses with much more sympathy than they appear to do at present".

Such social exclusion of the mentally ill when trying to access jobs and services is to be investigated by a new government consultation launched in May.

"We are determined to open up opportunities to people with mental health problems," said Social Exclusion Minister Barbara Roche - who is to chair a joint-ministerial steering group to oversee the project at the consultation launch with Health Minister Jacqui Smith. "This consultation will provide much needed insight into the barriers that people with mental health problems face when trying to get jobs and access services," she said.

The Social Exclusion Unit is expected to publish its final report in 2004. The consultation document can be found on: www.socialexclusionunit.gov.uk. The consultation period ends on September 5.