Environment Secretary Andrea Leadsom has insisted air quality is still a “top priority” for government and the draft plans will be published in June.

Her comments come as the government was due to publish a draft air quality plan by 4pm yesterday but it submitted a last-minute request for an extension until after the general election last Friday.

Ms Leadsom argued a delay is necessary to comply with purdah rules on government announcements during the election period.

She added the government has worked “very hard” to get the air quality plans ready, insisting it will be published “as soon as possible after the general election”.

The Environment Secretary said the deferral is “very short” and the draft publication in June, with a final report planned in September, “won’t delay implementation” as the government “absolutely intends to deal with issues to make sure the air is cleaner”.

While opposition parties criticised the government’s decision to tackle the toxic and illegal levels of air quality in the country, Ms Leadsom accused the previous Labour Government of encouraging people to buy diesel cars and make pollution worse.

She said this government “as ever, is trying to clean up a mess started by Labour”.

Yesterday, Shadow Environment Secretary Sue Hayman said Labour would publish an air quality plan “within the first 30 days” of administration.

Environmental lawyers ClientEarth, who brought legal proceedings against the government, previously said they are considering challenging the government.