STERILE mosquitoes are being released into the wild by experts to stop the spread of deadly diseases.

The Oxfordshire firm pioneering the technique has now been given an £8m boost to further its work.

The money raised by Oxitec, based at Milton Park, near Didcot, will pay for trials of the technique, which aims to reduce harmful populations.

Oxitec is commercialising research by Dr Luke Alphey at Oxford University, who developed a way of injecting mosquitoes with a chemical so their offspring die before they can mature.

Trials are hoped to show its effectiveness in combating dengue fever, known as ‘breakbone’, which infects more than 50 million people in tropical countries and kills more than 25,000 each year. No treatment or vaccine is available, and the technique would replace insecticides.

Trials have taken place in the Cayman Islands in the Caribbean where three million “sterile” mosquitoes were released into the wild.

Over a ten-hectare area, the results showed an 80 per cent drop in the mosquito population after 80 days.

Now “mosquito factories” are being developed in Milton Park and in Brazil to roll out the campaign to other countries including Malaysia, the United States and India.

Oxitec chief executive Haydn Parry said the technique was particularly effective against dengue fever as it involves only one species.

But he added that the aim was not to wipe out the mosquito population altogether.

Mr Parry said: “There are health benefits and it is much better from an environmental point of view.”

As a result of the successful trials, Oxitec has grown from 30 to 37 staff in the past year and will recruit another ten this year to work both here and overseas.

The £8m comes from Oxford Capital, of Cumnor Hill, which first backed the company in 2005, plus new investors from South America, Saudi Arabia and Asia.

David Mott, of Oxford Capital, said: “We have secured backing from investors in many of the countries where dengue is prevalent.”

Last month the company’s genetic engineering was criticised by Friends of the Earth, GeneWatch and Third World Network, which claimed the modified insects could trigger dangerous allergies.

But Mr Parry said the criticism was inaccurate . He said combating dengue relied on larvicides added to water, or chemical insecticides sprayed by helicopters into whole neighbourhoods.

He added: “The specific allegations are about a study that is already five years old and are extremely misleading."

Dr Alphey, chief scientific officer and founder of Oxitec, added: “We have been working on this for many years to ensure the approach is both effective and safe.”