Plans to promote electric vehicles in the UK do not go far enough to tackle air pollution, according to a leading government adviser.

Writing in the Guardian, Prof Frank Kelly said fewer cars, not just cleaner ones, were the key to cleaner air.

Prof Kelly said that London should lead the way in promoting non-polluting transport policies.

Just last week the government unveiled its strategy for tackling illegal levels of nitrogen dioxide in the air.

The key element was a promise to end the sale of all new diesel and petrol cars from 2040.

But according to Frank Kelly, who is professor of environmental health at Kings College London, and chair of the government advisory committee on the medical effects of air pollutants, these steps would not go far enough.

"Our cities need fewer cars, not just cleaner cars," Prof Kelly writes.

"One issue is that electric vehicles will not sufficiently reduce particulate matter (PM), the other toxic pollutant emitted by road transport.

"This is because PM components include not only engine emissions, but also a contribution from brake and tyre wear and road surface abrasion," he added.

The government has focussed on dealing with nitrogen dioxide because of consistent breaches of legal limits in many areas of the country.

According to the Royal College of Physicians the early deaths of around 29,000 people in the UK each year are linked to particle pollution, which is more than the 23,500 premature deaths attributed to nitrogen dioxide.

The combined total is estimated to be around 40,000 as some people are harmed by both pollutants.

"Electric vehicles have a role to play in tackling air pollution but they are not the only solution," said lawyer Anna Heslop.

"What we need, and what the government has so far failed to deliver, is a comprehensive plan to bring down air pollution in the UK."

Prof Kelly believes that attitudes towards cars are changing rapidly, with younger Londoners in particular opting for car club membership and ride-sharing apps instead of buying a car.

There should be "as much active transport in the form of walking and cycling as is feasibly possible," he says.

The Mayor of London, Sadiq Khan, has already committed the city to a future of fewer car journeys, aiming to cut the number by three million per day from 2041.

"Leaving the car at home must be the affordable, safest and most convenient option for Londoners going about their daily lives," Mr Khan said.

"This is not only essential for dealing with congestion as London grows, but crucial for reducing our toxic air pollution, and improving the health of all Londoners."