PLANS to ban high-polluting vehicles from Scotland’s city centres within the next few years are doomed to certain failure, campaigners have said.

Friends of the Earth Scotland insisted an extended “grace period” giving motorists time to acquire cleaner vehicles will mean low emission zones will not be fully operational until 2024-26 at the earliest.

It added: “This is nearly a decade after the Scottish Government and local authorities formally committed to introducing them, and fourteen to sixteen years after the binding European clean air deadline.”

Glasgow will become the first city in Scotland to introduce an LEZ from the beginning of next year. It will initially apply only to buses, before private cars are also brought under the strict regulations by the end of 2022.

But FoE Scotland has repeatedly criticised the Scottish Government’s LEZ legislation, insisting it lacks ambition and will not be enough to comply with clean air rules.

In evidence to a Holyrood committee, it attacked plans to ensure pollution-busting laws would not be enforceable for between one and four years for non-residents, and an additional one to two years for locals.

This so-called “grace period” is aimed at allowing drivers time to adapt.

The environmental charity said: "This sets up a timeline whereby LEZs will not be operational until 2024-2026.

“The Scottish Government formally promised that LEZs would be in place by 2018 in Glasgow, 2020 in Dundee, Aberdeen, and Edinburgh, and 2023 in other areas where necessary, in 2017.

“Cleaner Air for Scotland promises that Scotland will achieve compliance with EU legal limits on air quality by 2020.

“The grace period provisions condemn these promises to certain failure.”

The organisation also criticised the “weak” emission standards outlined in the legislation.

It added: “The long grace periods, combined with the fact that the emission standard…may be very weak, make the likelihood of seeing effective, enforceable LEZs on Scotland’s most polluted streets any time soon highly unlikely.”

A Transport Scotland spokesman said it took the issue of air pollution "very seriously".

He added: "Compared to the rest of the UK and other parts of Europe, Scotland enjoys a high level of air quality, but we cannot be complacent.

“We welcome the progress being made by Glasgow City Council with their plans for Scotland’s first LEZ to be in place by the end of 2018.

"As with the vast majority of LEZs across Europe, a lead-in time is a sensible measure, and this view was reflected in the LEZ consultation feedback from a variety of businesses.

“We are working closely with local authorities to put in place LEZs in Scotland’s four largest cities by 2020, which will improve public health by reducing pollution."