Glasgow charities could have thousands of pounds of funding clawed back by the council in bid to fill a budget black hole.

The cash-strapped local authority has to make more than £133million of savings in the next two years.

A leaked email seen by the Evening Times suggests council bean counters could ask charities to hand back money awarded through the Integrated Grant Fund (IGF).

The scheme offers cash to organisations “to deliver high quality and much needed services to the citizens of Glasgow”, according to the council website.

In December 2014 many charities were handed funding for three-year programmes, which could now be cut.

The local authority held crunch talks with charities this week to explain “the unprecedented and growing financial challenges” and prepare city groups for funding “revision”.

Glasgow Council for the Voluntary Sector, which represents more than 600 voluntary-managed organisations in the city, has warned the council there is nothing left to cut.

Councillor Susan Aitken, the leader of the SNP opposition at Glasgow City Council, fears much of the money already awarded has been spent and “retrospective cuts” could see some charities “go to the wall”.

A memo to “IGF Grant Recipients” from the council’s Head of Democratic Services, Jim Gray, which has been obtained by the Evening Times, said: “The council’s IGF is a valuable resource for the city however it will be very difficult for the council to meet this financial challenge while protecting the IGF.

“We therefore anticipate that we may have to revise some IGF awards made for 2016/17 and 2017/18. At this time, we anticipate that a report will be submitted to the Council’s Executive Committee outlining funding recommendations for 2016/17 and 2017/18, possibly in March 2016.

“We recognise that potential IGF funding uncertainty will be difficult and worrying for organisations however we wanted to provide you with enough notice so that you are able to properly plan and prepare for any potential revision of your IGF award.”

Helen Macneil, Chief Executive of Glasgow Council for the Voluntary Sector, said: “All third sector funds have already been hit hard in recent years, so there is no slack.

“IGF resources are already insufficient to meet the needs of the most vulnerable citizens in the city and any further cuts to this and other budgets will have a detrimental impact on both the really vital preventative work and crisis response work being delivered by voluntary sector organisations and groups in the city.”

Ms Macneil has written to the council to seek “immediate assurances” that the third sector will be protected.

Alan Benson, Chairman of the Third Sector Forum, has also slammed the council and warned that cutting cash for charities is a red line.

He said: “No third sector organisation should suffer any funding cuts. The news that the sector is facing cuts once again is alarming, particularly at a time when so many of these charities are facing an increased demand for their services.

“Many organisations have told the Third Sector Forum they are already on a knife edge and even the smallest cut would place them in an unbearable situation.”

Councillor Susan Aitken, leader of the SNP opposition at Glasgow City Council, accused the local authority of “moving the funding goalposts” and warned that any cuts could be “a disaster for many third sector organisations in the city, particularly smaller, neighbourhood-based groups”.

“A three year grant funding deal was agreed on the understanding that this would provide organisations with some stability and the ability to plan ahead, and many organisations will – in good faith – have already committed the funds they were told they could expect,” she said.

“To now tell them all that might be retrospectively changed will cause enormous concern, disruption and stress, for the people working in the third sector and for the Glaswegians who use and greatly value the services it provides.”

Ms Aitken added: “Community organisations provide preventative services and support that save the council and the wider public sector incalculable amounts of money. The Labour administration must say whether it is committed to building a sustainable future for the third sector in Glasgow, or if it is happy to risk sending these organisations to the wall.”

After the Evening Times got in touch with the council Mr Gray issued a second email to charities which guaranteed existing funding until June 30 2016.

But he said organisations should “note that this does not guarantee that your IGF award will not be revised for the remainder of the 2016/17 and 2017/18 financial years.”

Mr Gray also set out how the local authority will “support” charities facing a funding cut, including offering help with “restructuring and downsizing”.

A council spokesman said: “At this stage, no decisions have been taken about the possible revision of funding and the council’s budget for next year will be set on March 10.”