More than half of Glasgow City Council staff said working for the local authority had become worse in the last three years, according to an internal investigation.

The finding of the first staff survey since 2012 have not been released publicly but The Evening Times has obtained a copy of the document.

The results of the questionnaire, which was completed by thousands of employees, showed that 60% reported that working conditions had deteriorated while only 14% said there had been an improvement.

A third of staff who indicated that working for the council had become worse said they were unhappy because they had been asked to take on additional responsibilities and work longer hours with no financial reward.

Land and Environmental Services staff are considerably less likely than average to be satisfied with working life at the council.

A quarter of staff surveyed said they had been bullied in the last three years while only a third who were targeted had reported it. Half of those that did make a complaint said they had not been properly supported through the process.

The Evening Times revealed recently that 28,000 working days were lost to Labour-led Glasgow City Council and it’s arm’s-length organisations through industrial action in only five years.

Trade union Unison, which represents a majority of council workers, said the findings show that the council must invest in its workforce.

Glasgow branch secretary Brian Smith said: “After five years of cuts in jobs, services and living standards it is no surprise that a clear majority of workers believe that working for the council has become worse.

“The fact that the most common reason for this is overwork confirms what trade union members on the frontline have been saying for some time that we need more workers and resources to care for the city’s older and vulnerable people, educate our children and protect our local environment.

“Low morale and overwork also have a very real effect on the health of workers and the trade unions are sick of the council making our members sick.

“The Glasgow trade unions will now be stepping up the campaign against the £100million cuts and 3,000 job losses planned in 2016.”

The SNP has also criticised the council and called for constructive dialogue with trade unions.

Leader of the opposition, Councillor Susan Aitken, said: “The SNP in Glasgow is absolutely committed to running a council which treats staff well and encourages everyone to be their best at all times. We know that a happy workforce is one that is innovative, motivated and productive.

“This survey shows that while many employees are content in their jobs, many staff feel that working for the Council has deteriorated since 2012. It’s vital that in these circumstances, employers, employees and union representatives come together and improve relations in the workplace.

“All of our staff should feel that the Council is a great place to work, where their views are considered and where they feel informed and engaged. It appears that large numbers of Council staff don’t feel that way. It is vital that the Council turns this round.

“I am particularly concerned at the levels of morale and job satisfaction in our Land and Environmental Services department. Many of these workers have borne the brunt of changes to staff terms and conditions and this is reflected in the negative levels of satisfaction with work, conditions and facilities.

“Our staff should feel safe at work and, when bullying takes place, the Council should provide every support necessary to employees. I am disappointed that so many staff feel that the Council doesn’t provide enough support during the bullying reporting process.”

Ms Aitken said she would take steps to improve working conditions if the SNP takes control of the local authority following local elections in 2017.

She added: “We are clear that positive industrial relations make for a happier, more productive workforce. We will work hard to make that aspiration a reality.”

A spokeswoman for the council said an “action plan” to address the issues raised in the survey will be agreed “in the next six months”.

Labour councillor Matt Kerr, who is responsible for personnel at the local authority said he is working hard to mitigate the impact of budget cuts.

He said: “The scale of the cuts imposed on Glasgow City Council in the last few years have forced us to change how we work, and to continue to deliver excellent services with fewer staff.

“We have made substantial strides in removing work from the system but it appears that these cuts, which are completely out with the council's control, may be having an impact on staff morale.

“However staff clearly understand and accept the need for the council to change, they remain committed to working for the council, and they are proud of the service they deliver.

“I look forward to working with our colleagues in the trade union movement to make change work for our staff, but also in the fight to halt the continued disproportionate cuts to Glasgow.”