Birmingham's clean air zone could be delayed further after errors were discovered with the Government's new online vehicle checker.

The platform, which is supposed to help drivers and businesses prepare for CAZs in Birmingham and Leeds, was launched last week.

However, the data’s accuracy has been questioned after it appeared to show some cars were compliant for Birmingham’s CAZ when in fact they would face a daily charge of £8 to access the city centre.

Transport Secretary Grant Schapps has called for “urgent work” on the checker, saying it is “not up to scratch”.

The software, which was being delivered by the Government’s Joint Air Quality Unit (JAQU), was expected to be ready by October 2019.

However, JAQU (a joint unit between DfT and DEFRA) told the councils last June that the new system would not be delayed until the start of this year.

As a result, both councils said their clean air zones would not be introduced until July, at the earliest.

Now, the Birmingham scheme could be delayed further, while the problem is resolved.

“The Government has recognised the teething problems with its clean air zone vehicle checker and is working to iron out any issues as quickly as possible,” said a Birmingham City Council spokesman.

“Once those issues are resolved, there needs to be a period for motorists to check and prepare - and it has been suggested that this be a six-month period in fairness to all concerned.

“The key message is that if you are driving a Euro 4 petrol vehicle or Euro 6 diesel your vehicle will be compliant with Birmingham’s CAZ.”

RAC spokesman Rod Dennis said: “It’s somewhat unfortunate that the only thing holding Britain’s second biggest city back from reducing vehicle emissions is a website, so it’s right this issue gets looked at urgently.

“The alternative would have been some non-compliant cars driving into Birmingham’s clean air zone, and drivers of compliant ones getting wrongly charged.

“But it’s disappointing these issues haven’t been dealt with much sooner, especially as we’ve been calling for a conclusive online look-up system ever since the Government announced its air quality strategy back in 2017.

“This is a confusing time for drivers so having certainty about whether they face charges or not is paramount. Anything short of a single, definitive online vehicle checker isn’t really acceptable.”

For the latest on the cities considering air quality restrictions, go to our interactive clean air zone map.