Cheshire East Council has apologised after admitting its air quality figures were deliberately tampered with for three years.

In a statement, the local authority said ‘deliberate and systematic manipulation’ of the data from its air quality monitoring stations around the country took place between 2012 and 2014.

The statement follows an external investigation, after concerns were raised at cabinet last year.

According to the council, the investigation found incorrect air quality data was submitted to the Department for the Environment, Food and Rural Affairs, which will need to be corrected.

It added the figures, which are known to have been altered, are ‘spread over a wide geographical area, which implies that the manipulation was not motivated by a wish to favour specific sites’.

And the local authority said the errors have also affected air quality assessments, which were carried out for planning applications in areas such as Nantwich, Congleton and Crewe.

‘On behalf of the council I would like to sincerely apologise in respect of these findings, we would like to assure everyone that we have done everything we can to rectify these failings,’ said the council’s director of planning and sustainable development, Sean Hannaby.

‘It is worth reiterating that in July 2016 the-then director of public health assured us that there are no immediate health protection measures needed as a result of these errors and I have been assured that this advice still stands.

‘We appreciate that it has been a year now since we first reported these concerns, but it was important that we ensured a thorough review and investigation into this important matter,’ added Mr Hannaby.

‘Significant work has been undertaken to ensure that there are now robust processes and procedures in place. The planning service is currently analysing the relevant planning applications to assess whether any additional mitigation measures are required.’