The government must not punish motorists who drive diesel vehicles, a prominent rural MP has warned.

Diesel vehicles emit far higher levels of nitrogen oxides than petrol vehicles – prompting increasing calls for their use to be curtailed in an effort to improve air quality.

But any move could hit rural communities particularly hard because many rural residents use diesel vehicles as opposed to other forms of transport.

Neil Parish, who chairs the House of Commons rural select committee, said a scrappage scheme should be introduced if the government wanted to get rid of the most polluting cars.

Poor air quality was a "public health emergency," said Mr Parish on Wednesday (19 April).

But it would be wrong for the government to punish diesel drivers for taking the advice of a previous Labour government which encouraged motorists to buy the vehicles.

Instead, the government should offer a 'carrot and stick approach' to get the dirtiest diesels off the road, Mr Parish suggested.

Any scheme should be targeted, providing money towards newer cleaner forms of transport, particularly in the pollution hot spots, he said.

Air quality is more of a problem in inner city areas than the countryside.

Some 60% of the nitric oxide in inner cities comes from transport, said Mr Parish.

"It is quite difficult to break that down and say how much comes from buses, taxies, lorries, delivery vans and cars," he said.

"But there is no doubt that tackling the private car, particularly in those spots, will help to make a real difference in reducing NOx emissions.

"Transport is a particular issue, as is the older diesel engine. We cannot ignore what is going on; we need to take action."

Mr Parish said motorists were encouraged to switch to diesel through changes to the vehicle taxation system under a previous government.

"We now know that that was a policy mistake. The uptake of diesel cars rocketed. The proportion of diesel vehicles on British roads increased from 20% in 2005 to 37.8% in 2015.

"That was a deliberate government policy. Between 2005 and 2015, we did see cleaner diesel vehicles, but naturally they still give off particulates and NOx."

In turn, the number of extra diesel vehicles had caused a host of air quality problems. Diesel engines emitted a higher level of nitrogen oxides.

Those gases caused or worsened health conditions such as asthma and bronchitis and even increased the risk of heart attacks and strokes.

"They are linked to tens of thousands of premature deaths in Britain every year," said Mr Parish.

"As a result, the Select Committee on Environment, Food and Rural Affairs, which I chair, branded poor air quality a "public health emergency" in our recent report to the Government.

"Four in 10 local authorities breached legal nitrogen dioxide limits last year. That shocking statistic shows the scale of the problem.