Policies encouraging the massive rise in the number of diesel vehicles could be responsible for thousands of premature deaths in the UK, according to the Government’s chief adviser on air pollution.

Professor Frank Kelly, chair of the Department of Health’s committee on air pollution, said particulates from diesel engines could be responsible for around 25% of all air pollution deaths. Government figures show around 29,000 people die prematurely from air pollution every year.

He said: “We have walked blindly into a situation where we have a high percentage of diesels in the transport sector. All taxis and buses are diesel. From one in 10 private cars being diesel in 2000 it is now nearly half today.

“A lot of the minute particulate matter comes from diesels in cities. It is estimated that 50% of the particulate matter in London is from transport and that diesel makes up about half of all the transport," he said.

Diesel vehicles have been popular with motorists and encouraged by government because they are more fuel efficient and cut CO2 emissions.