Plans for Scotland’s first low emission zone (LEZ) in Glasgow have been branded “half-hearted” by the Greens.

Co-convener Patrick Harvie raised criticisms of the proposals during First Minister’s Questions at Holyrood.

The zone – due to come into effect at the start of 2019 – will initially crack down on bus pollution, with all vehicles to be compliant with restricted emissions in the city centre by the end of 2022.

It has been criticised by Friends of the Earth Scotland as a “no ambition zone”.

Mr Harvie said: “We’ve got a responsibility to make sure that this first zone in the country doesn’t set a precedent for weak action because dozens of other communities around Scotland need to see a sense of urgency.

“As it stands, this half-hearted plan would still guarantee that Glasgow fails to achieve clean air by the government’s own target date.

“Even using the government environment agency Sepa’s own figures, their own analysis of the impact of this, it is impossible for the low emission zone as currently proposed by the city council to eliminate illegal air pollution levels in Glasgow on the timescale that’s being set out.”

Addressing Nicola Sturgeon, he added there was a “genuine concern that it’s her government’s agency Transport Scotland that seems once again to be the biggest barrier to change, accepting the self-interested arguments of profit-driven bus companies.

“Will she take on the cautious business-as-usual attitude at Transport Scotland and turn it into a catalyst for change pushing the agenda forward, getting the resources spent and challenging councils to do more instead of holding them back?”

Ms Sturgeon said she did not accept Mr Harvie’s characterisation of the plans or of Transport Scotland’s involvement.

She said the proposals comprised one of the “most challenging, all encompassing LEZs in Europe”.

Ms Sturgeon acknowledged frustration over the lead-in times but said these were based on pragmatism to allow vehicles the time to adapt.

She said discussion and debate would continue as the plans develop to look at where improvements could be made.