A government bid to delay plans to tackle illegal levels of air pollution in Scotland and the rest of the UK have been rejected by the High Court.

The court has now given UK ministers a new deadline of 4pm on May 9 for the plans to be made public.

The government was ordered by the court last November to produce an Air Quality Plan to tackle illegal pollution levels across the UK by 4pm on Monday.

But on Friday after the court closed, and less than one working day before the judge-imposed deadline, government lawyers applied to defer publication until after the general election.

The presiding High Court judge also refused to grant permission to appeal, saying the government would have to go direct to the Appeal Court if it wishes to appeal the decision.

The court ruled that there was "no adequate explanation" to back up the government's assertion that a delay in publishing the draft plan would not delay its implementation, adding that the impact of air pollution made it the impacts of air pollution were "exceptional public health circumstances".

James Eadie QC, representing the government, had told the court that the draft plan was “ready to go” but should be delayed because of purdah designed to stop political parties using the machinery of government for electoral advantage in the run-up to an election.

But Mr Justice Garnham said that purdah, the pre-election period,  does not affect the outcome of a High Court case and "is not a trump card to be deployed at will by one litigant," with the judge adding that the government must comply with a court order like anyone else.

The Government was ordered to publish updated clean air proposals by April 24, after courts ruled existing plans to meet EU-mandated air quality limits, which are being broken across many areas of the country, were not sufficient.

The development comes just two months after it emerged Britain faced multi-million pound fines if it does not heed a final warning by the European Commission over its failure to address harmful levels of toxic air in the UK, with Scotland amongst the worst offenders in the country.

The Herald:

The new plans that meet the legal requirement to cut illegal levels of nitrogen dioxide pollution in the “shortest possible time” was expected to involve clean air zones in many cities and towns across the country.

But the Department for Environment, Food and Rural Affairs applied last week to delay publication

Mr Eadie told the court that Sue Gray, a Cabinet Office official, had raised “serious concerns about the appropriateness of publishing this in the sensitive period” given the impending general and local elections. He claimed publication of the plan would “drop a matter of key controversy into particular localities” and a “controversial bomb” into the mix of local and general elections.

But environmental lawyers ClientEarth said there should be no delay in publication saying the issue of air quality is a “huge issue of public concern”.

Some 2000 early deaths are caused every year in Scotland because of polluted air according to the latest medical research, with some 40,000 across the UK.

Glasgow has been described as "the most polluted city in Scotland" by environmental lawyers ClientEarth over what it called "illegal and harmful levels" of nitrogen dioxide (NO2), which comes mostly from diesel vehicles.

Data produced by the EU shows that Glasgow has the highest average annual concentration of NO2 outside of London, with 68 micrograms of NO2 per cubic metre of air - 70 per cent higher than the Euro limit.

A Downing Street spokesman said: "We will consider the judgement and then decide what we do next."