There is growing concern over the safety of using mobile phones.

BBC News Online examines the latest evidence and advice on keeping any perceived risks to a minimum.

Are mobile phones safe?

Nobody really knows that answer to this question and it has been the subject of fierce debate for many years.

There is currently no scientific evidence to suggest that mobile phones pose a risk to health.

However, since mobile phones are a relatively new technology there has been no research examining the long-term effects of using handsets.

Experts have suggested that any perceived risks can be kept to a minimum by keeping mobile phone conversations short and using hands-free kits for longer conversations.

What are the possible risks?

There are fears that the electromagnetic radiation emitted from mobile phone handsets may adversely affect the body's cells, brain or immune system and increase the risk of developing a range of diseases from cancer to Alzheimer's.

While there is no evidence to back up these fears, laboratory tests on mice have shown that the radiation from mobile phones can have an adverse effect on their overall health.

It is not clear whether those findings can be applied directly to humans.

A study by scientists in Finland suggested that the electromagnetic radiation did affect human brain tissue.

But they played down their findings saying more research was needed to see if the effects were the same in living people.

There have also been reports of people suffering from headaches, fatigue and loss of concentration after using their mobile phones. However, again these claims have not been scientifically substantiated.

What is the government's view?

The UK government commissioned a major study into the safety of mobile phones.

In 2000, the Independent Expert Group on Mobile Phones published its report.

The Stewart report, named after the group's chairman Sir William Stewart, concluded that there were no health risks associated with using mobile phones.

However, it suggested that children should be especially careful about using mobile phones and recommended that only essential calls should be made and that these should be kept as short as possible.

In January, a £7.4m research programme was announced, backed by the government and the mobile phone industry, to be managed by an international committee of experts led by Sir William.

The programme includes 15 studies which will seek clear conclusions about the health hazards of mobile phones, in particular fears of an association between radiation and brain cancer.

The main purpose of the research will be to see whether "subtle biological changes" already known to be caused by mobile phones pose a risk.

What is the industry's view?

The mobile phone industry has spent millions of pounds investigating the safety of handsets.

It is adamant that there is no link between the use of mobile phones and any adverse human health effects.

What steps can people take to reduce any risk?

Experts suggest that mobile phone users can take a number of precautions to reduce any possible health risks.

Practically all agree that the best step is to keep mobile phone conversations short and to a minimum.

Many believe that so-called hands free kits also reduce the risks by cutting the amount of electromagnetic radiation entering the brain.

They also recommend that users buy phones with external aerials so that it is as far away from the head as possible when in use.

Similarly, it is believed that phones with a long talk time are more efficient and produce less powerful emissions.

Users are also advised against buying handsets with a high "SAR" value, which means it emits more radiation.