Sheffield Council has run a project called the Sheffield Showcase in city centre shop windows which were left vacant when an ambitious retail redevelopment stalled as a result of the economic downturn.
In the last 18 months the council has spent more than 188,000 setting up the scheme – which offers local firms free advertising – and paying its running costs, including electricity bills, window cleaning and legal fees.
But plans to spend a further 53,708 on the project this year have been branded "ridiculous" by trade unions, whose members have been sent letters by council chiefs warning them of possible redundancy.
Regional organiser for the GMB union Peter Davies said spending money on a "cosmetics job" was an insult to workers who have been told their jobs are at risk because of Government cuts.
Mr Davies questioned why Hammerson, the developer behind the stalled Sevenstone retail scheme, had not contributed towards the costs and said: "There have got to be far higher priorities.
"At a time when we really don't know how we're going to keep our streets clean or look after the elderly, do we really need to care about the cosmetic appearance of shops? It's a waste of 53,000.
"That money could be used to protect the jobs of two or three care workers, with on-costs. They will be angry that the council is spending money in this way."
Last September, Sheffield Council sent 8,500 of its employees official HR1 notices after revealing it needed to make savings of 220m over the next four years under Government austerity cuts.
Negotiations between the council and unions continue, but Mr Davies said the windows scheme raised "serious questions" for the Lib Dem-run authority.
He added: "You have got to ask: Is this the tip of the iceberg? What else are they spending money on?
"It is about essential spend. This is not essential when you are talking about looking after the most vulnerable in society and keeping essential public services going."
The units involved in the Sheffield Showcase scheme were bought under compulsory purchase orders in 2007 when plans for the city's Sevenstone retail quarter were still on schedule.
Some of the buildings were set to be demolished to make way for new outlets, including a purpose-built branch of department store John Lewis.
But the shops, which are in the busy Pinstone Street area of the city, have been empty for almost two years after Hammerson said it was unable to continue because of the economic outlook.
Since the Showcase began, the council has spent 1,170 on window cleaning, 3,510 on electricity for the shops and nearly 30,000 on other set up costs and legal fees.
Sheffield Council's ruling cabinet will be asked at a meeting on Wednesday to approve the extra spending on the project, which will allow it to continue until the end of December this year.
Negotiations between the council and Hammerson continue on the Sevenstone scheme's future.
Last night council leader Paul Scriven defended the showcase and said the authority had worked with city retail academy The Source, whose students had gained valuable experience in their trade by dressing the shops.
He added: "The trade union officials in the public sector have got to get into the real world.
"This project not only improves the look of the city centre but stimulates investment from the private sector, which is where the future of Sheffield lies.
"It has been used as a training and development platform for the students and their work has actually attracted other businesses to open in that area.
"Several shops and a bar have set up for business in some of the empty shops as a result of the showcase, bringing real jobs for people in Sheffield.
"Sheffield Showcase has stopped the city looking shabby and the investment has delivered real growth not just window dressing."