Transport secretary Mark Harper should use the law to intervene in the battle to scrap the Ultra Low Emission Zone (ULEZ) in Kent.

That’s according to campaigners who claim the government minister has the legal weight to force Labour London Mayor Sadiq Khan to "revise" a controversial transport policy seen as damaging to people outside of his authority area.

The move was made by Kent resident Amanda Bullen with a Change.org petition which has gained more than 16,000 signatures of its 25,000 target.

Parts of Kent which are London boroughs, like Bexley and Bromley, and not part of Kent County Council or Medway Council, were included in the expanded ULEZ scheme on August 29.

Originally, it started in central London with the aim of improving air quality by deterring motorists, through a £12.50 charge, to drive older, polluting cars into the zone.

Failure to pay the charge risks a £180 fine, reduced to £90 if paid within 14 days.

The charge is meant to encourage drivers to swap over to lower emitting vehicles but critics say it penalises the poor.

The petitioner claims section 143 of the Great London Authority Act 1999 gives the Secretary of State powers to revise transport strategies which are "inconsistent with national policies" and which may be detrimental to any area outside of its immediate jurisdiction.

Oxford-educated Mr Harper, MP for the Forest of Dean, Gloucs, and unaffected by ULEZ, can make such revision, say campaigners.

The London mayor has faced strong opposition to the scheme, although a £160 million scheme run by Transport for London (TfL) enables Londoners to claim grants to make the swap non-compliant cars with greener replacements residents, small businesses, sole traders and charities scrapping non-compliant cars to claim grants.

But Roads minister Richard Holden told the Local Democracy Reporting Service: "I am not aware of the petition but the department did look at it at the time.

“As I understand it, Mark (Harper) took legal advice and was told it (section 143) couldn't be used."

In August, Mr Harper said: “I don’t have the power to stop it coming into force.

“That’s a decision for the mayor of London backed by the Labour leader. I think he should think again.

“He says this has to do with air quality, his own impact assessment says this will only have a minor to negligible effect on air pollution."

Kent County Council has also registered its opposition to the plan.

A motion stated: “...this council condemns the implementation of the London ULEZ expansion that will impact business and separate families and friends who live in Kent from those who live in the historic parts of Kent that are now within the Greater London boundary, disproportionately hitting essential key workers and those on low incomes who cannot afford to buy new, compliant cars and therefore call upon the Mayor of London to reverse this decision.”

Labour, riding high in the polls under leader Sir Keir Starmer, is fearful ULEZ will become a London election issue next year when Prime Minister Rishi Sunak is expected to go to the polls.

Having narrowly retained the Uxbridge and South Ruislip seat at Westminster at a by-election (where the Tories were predicted to lose), ULEZ's unpopularity could be used to attack Labour.

The petitioner argues that the expanded ULEZ scheme is detrimental on a number of fronts. She says it is unfair to low paid workers such as carers, NHS staff and shift workers; the grant scheme is insufficient; a lack of alternative public transport; the cost of living crisis and a waiting list for suitable new cars.

Mr Khan has always defended his plan, arguing it is a difficult but necessary decision that will prevent deaths and improve the capital’s air quality.

The recent expansion introduced ULEZ to all Greater London boroughs and up to the border with Kent and other home counties.

Lynne Tozeland wrote on the Change.org comments section: "ULEZ expansion will not make any difference to air quality in outer London but will cause huge hardship to people living in outer boroughs and surrounding counties."