Toxic moths which can cause skin rashes, conjunctivitis, sore throats and breathing problems have been discovered in Park Royal, west London.

The Oak Processionary Moths, which are usually found in southern and central Europe, are currently at caterpillar stage - which is when they pose a risk to the public.

Experts warned that their microscopic hairs, known as setae, can be spread by wind and affect people exposed up to 20 metres away.

Direct or indirect contact with the tiny hairs can provoke allergic reactions such as rashes and eye infections.

In the most serious cases, small numbers of people suffer breathing difficulty similar to asthma.

The hairs contain a toxin which releases histamine in humans and provokes the allergic reaction.

The moth, which is covered in as many as 63,000 bristles, has caused outbreaks in Austria, Belgium and Holland in recent years.

They were first discovered in London last spring when a number of people suffered reactions.

Experts were surprised to find that they had survived the cold English winter and had once again flourished in the oak park.

An emergency "outbreak meeting" between the Forestry Commission, Health Protection Agency and local authorities will be held in London on Wednesday.

Forestry Commission spokesman Charlton Clark said: "We are looking at a number of ways to eradicate the moth from Park Royal, including destroying the nests or spraying them with a hair-spray type substance to lock their tiny hairs.

"We would discourage members of the public from tackling the nests themselves, as this can only be done by trained professionals with protective clothing."

Mr Clark said that although climate change had not been confirmed as the cause of the outbreak, the mild winter had helped the moth to survive.

Ealing Council leader John Stacey said: "There is a chance that people could come into direct or indirect contact with the caterpillars' microscopic hair.

"We don't want to alarm anyone, but we fell it is right to inform people so that they are aware of the situation and know what symptoms to look out for.

"All the relevant agencies are working in partnership to remove the caterpillars and make the area safe."

Anyone concerned that they may be suffering the symptoms should telephone NHS Direct's 24 hour helpline on 0845 4647 or visit their GP.

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