Rishi Sunak told his bid to block Ulez expansion would fail

Ministers wanted to block the expansion under laws to oppose plans that are ‘inconsistent with national policies’

Rishi Sunak’s bid to overrule Sadiq Khan’s expansion of the ultra-low emission zone (Ulez) was dropped after lawyers told him it would fail in court, it has emerged.

Ministers were considering a bid to block the expansion of the scheme, introduced to tackle air pollution in the capital, using a legal power under which they can oppose plans that are “inconsistent with national policies”.

The 1999 Greater London Authority Act states a transport secretary can order the mayor to revise policies that go against national policies and are “detrimental to any area outside Greater London”.

But legal advice commissioned by the government concluded an attempt to block the expansion under the provision would fail if challenged, The Telegraph reported.

Mr Khan said instead of attacking the power of devolved mayors, the prime minister should be “working with us and fulfilling his legal obligation to tackle the UK’s toxic air pollution”.

Hitting back at the inference his Ulez expansion could go against the government’s policies, he said: “Birmingham, Bath, Sheffield and Tyneside all have clean air zones, funded by the government.

“Does the PM want people there to breathe dirty air too? Or just London?”

Ulez, which costs drivers of vehicles that do not meet minimum emissions standards £12.50 a day to enter, is set to expand to all London boroughs from August 29.

The expansion has proved controversial, with the Conservatives citing anger against it for the party’s shock victory in last month’s Uxbridge and South Ruislip by-election – to replace former prime minister and local MP Boris Johnson.

And Mr Khan has faced pressure from within his own party, with Labour leader Sir Keir Starmer asking him to reflect on the expansion in the wake of the Uxbridge defeat.

Sir Keir said the charge was “disproportionately” hitting hard-up Britons during the cost of living crisis and said cities should look at “other ways” to tackle air pollution.

The Conservatives have said Sadiq Khan’s administration was attempting to ‘silence’ academic challenges to Ulez (Lucy North/PA) (PA Wire)

But Mr Khan has refused to “delay, water down or step back” on “vital public health and green policies”.

Instead, he has expanded a support scheme to offer every Londoner with a polluting car a grant of up to £2,000 to switch to a greener model, while small businesses can get £21,000 to junk up to three vans.

No10’s bid to block the Ulez expansion comes after Mr Khan was accused of attempting to “squash dissent”, after his deputy asked a City Hall-funded expert to counter scientific views that questioned the benefits of a charge on polluting vehicles.

Despite legal advice against the move, Tory MPs urged ministers to intervene anyway. Greg Smith told The Telegraph it would be “perfectly legitimate for national government to step in and stop this crazy, nonsensical, punishing idea”.

A Downing Street source told The Telegraph: “We have and continue to look at options, but they are limited.

“The people who could stop this tomorrow are the Labour Mayor Sadiq Khan and Sir Keir Starmer.”

A Department for Transport spokesman said: “It is for the mayor to justify the Ulez expansion, and at a time when the government is doing everything it can to support people with the cost of living, the mayor is responsible for explaining whether it is fair to charge those with non-compliant vehicles £12.50 every time they drive in London.”