Image caption The charges were due to be introduced in January in Leeds and Birmingham

The introduction of Clean Air Zones in Birmingham and Leeds has been "significantly postponed" due to a government delay, councils say.

Vehicle checking software required to make the zones operational and enforceable was expected to be delivered by the government by October.

The cities' councils say the tool has been delayed until December, which will put back the January start date.

The government has been contacted for a response.

Leeds City Council and Birmingham City Council were asked to tackle air pollution as a priority after roads in the cities were identified as likely to fail legal air quality levels by 2020.

Birmingham said its new zone would now not come into force in July 2020, at the earliest.

A revised date for the scheme to start in Leeds has not yet been announced.

In a joint statement, the councils said they "had been on track to implement Clean Air Zones on the basis that a vehicle checker tool, which is being delivered by the government's Joint Air Quality Unit (JAQU), would be ready by October 2019 as planned.

"However, JAQU has now confirmed that the vehicle checker will not be available until at least December 2019 - leaving just weeks before the zones were due to come into force in January 2020."

Image copyright OpenStreetMap Image caption Leeds' zone will see a £50 daily charge for non-compliant buses, coaches, and HGVs, with a £12.50 charge for non-compliant taxi and private hire vehicles

Leeds City Council said it had successfully met "a number of challenging deadlines" only for the government to "fail to meet its own commitments".

Councillor James Lewis, deputy leader, said: "The government now needs to outline new timescales that they are confident can be delivered in order to give residents and businesses across the country clarity and certainty."

It said it would still be installing the camera infrastructure required for the zone in the coming weeks.

Image copyright Birmingham City Council Image caption The zone in Birmingham will see motorists in petrol cars built before 2006 and diesels before 2015 charged £8 to drive inside the A4540 ring road

Birmingham City Council's cabinet member for transport and environment, Waseem Zaffar, said sticking with the January start "would be completely unfair on residents, businesses and visitors to the city".

"This is simply unacceptable," he added.