A trade union boss has warned that Glasgow city council could effectively become bankrupt over £250m worth of new equal pay claims.

Gary Smith, who leads the GMB in Scotland, said a fresh round of claims would be submitted by female workers months after an initial £500m settlement was secured.

He said he feared Glasgow could become like a US city that famously went bust: "It could be Detroit without the soundtrack."

However, SNP council leader Susan Aitken hit back yesterday: “These are nonsense figures, plucked from thin air – and it is worth remembering that pretty much every single prediction anyone has ever made about this has been wrong."

Earlier this year, the city council appeared to end a long-running dispute with thousands of female staff who had been paid less than men on the same grade.

The council challenged the claims for years before the incoming SNP administration changed tacked and settled.

The local authority’s strategy for meeting the £500m bill was for a council spin-off firm to take a loan out against the city’s publicly-owned buildings. Women are in line for an average payment of £35,000.

However, the disputed pay structure is still in place and the GMB, which represents many of the staff, is helping female workers put in a new wave of claims.

Smith’s GMB union was criticised in previous years for not doing enough to help the female workers, but his appointment in 2015 led to a rethink and his colleagues have since vigorously represented the women.

Speaking to the Herald on Sunday, Smith said the £500m may only be the beginning for the council:

“The women are still being discriminated against in Glasgow because there is not a new pay and grading structure in place. For every second these women are at work they are losing out.

“As new people are employed by the council, as soon as they start, many of them are going to have claims against the council as well. The council is paying out £500-plus million, and it is immediately racking up the credit card bill again.”

He put a figure on what the new bill may come to: “By 2021 the city council will need to find at least another £250 million to fully settle its historic sex discrimination against its employees and it will need to implement a new job evaluation system to address that discrimination once and for all.”

Smith is worried that Glasgow may fail to pay its bills: “I don’t know, in real terms, if cities can go bankrupt in the UK, but to all intents and purposes Glasgow is going to run out of money. If you want to call that bankruptcy, fine.

"At some point, the Scottish Government is going to have to step in. You cannot keep remortgaging all the buildings in Glasgow. You can’t keep cutting services."

“There is a precedent for cities going bust elsewhere in the world. I don’t think you can let Scotland’s biggest city go bankrupt, but something has got to be done to reverse the decline of Glasgow and, once and for all, sort out the debts.”

The SNP currently runs the council, but Smith says the political blame predates Nationalist control: “You have got an administration now that is dealing with generations of mismanagement. You cannot heap all the blame on the current political administration, but there is no easy way out of this.”

However, he is angry that council officials who he regards as responsible for past mistakes are still in post.

“On the face of it, it feels like the people who were there when we got into this mess are still there now. And that is pretty staggering,” he said.

Aitken added: “Until we implement a new pay scheme, there will be further equal pay claims to settle. Everybody knows that – it was in the paper we took to committee. We are factoring this into our funding strategy. However, the claims will be smaller in number and they will also cover a far shorter period.”