Motorists could face pay-per-mile driving charges under London Mayor Sadiq Khan's plans to hit Net Zero targets, Tories have claimed, despite Khan having "ruled out" the option being enforced during his tenure.

The Mayor has spoken positively about a pay-per-mile system in the past - which could see the end of the Ulez scheme altogether - and though he has shut down suggestions of actually implementing it, Khan has locked horns with Conservative mayoral candidate Susan Hall ahead of London's elections on May 2.

Conservatives have highlighted how the mayor's official transport strategy includes a commitment to "investigate proposals for the next generation of road-user charging", and have said that Khan's 2030 Net Zero targets in the capital are reliant on such measures.

The Mayor proposed the 2030 target in 2020, before enshrining it in his 2021 re-election manifesto.

This year's manifesto, published on Thursday, says: "We have an ambitious target of making London a net zero-carbon city by 2030 - faster than any comparable city".

Khan had previously commissioned research by sustainability consultancy firm Element Energy, which published a report on potential "pathways" to carbon neutrality in January 2022 - which said that "all scenarios would benefit from London-wide road user charging being introduced as early as possible", and described charging as "one of the key early building blocks of any package".

The pathway the Mayor chose - an "accelerated green" pathway - requires "London-wide road-user charging" from the "mid-late 2020s" in order to reach Net Zero.

In a formal response to the report, Khan said: "The scale of reductions required - a 27 per cent reduction in vehicle kilometres according to the 'accelerated green' scenario - is only possible with some form of road user charging.

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"Such a system could abolish all existing road user charges - such as the Congestion Charge and Ulez (Ultra Low Emission Zone) - and replace them with a simple and fair scheme where drivers pay per mile, with different rates depending on how polluting vehicles are, the level of congestion in the area and access to public transport."

But when questioned by Conservative London Assembly Member Emma Best on pay-per-mile last year, Khan was bullish in shutting down claims he would implement such a system, stating: "I want to be crystal clear. A pay-per-mile scheme is not on the table and not on my agenda. I will not move the goalposts on Ulez emission standards."

Tories have also flagged that Khan’s 2023 book, Breathe, states: "we have plans to introduce a new, more comprehensive, road user charging system."

In response to those claims, Hackney Labour councillor Mete Coban said Breathe was a "personal book... Not the manifesto for London", addiing that "Sadiq has ruled out pay-per-mile for now".

But Susan Hall told the Telegraph there was "no doubt that he will put [pay-per-mile] in", adding: "We've seen all the evidence."

A spokesman for the Mayor said: "Sadiq has repeatedly and categorically ruled out pay-per-mile for as long as he is mayor.

"It will not be introduced in London, despite misleading statements from the Tories saying otherwise.

"The road-user charging scheme was originally proposed by Boris Johnson as Mayor and by Rishi Sunak as Chancellor... Sadiq has repeatedly ruled out any such scheme while he is Mayor."