Staff at Scotland's colleges are under "extreme pressure" after budget cuts and a series of mergers, union leaders have claimed.

A survey of Unison members found almost two-thirds (64%) believe the service has worsened over the last two years, with only 15% believing that things have got better.

Staff morale was described as being at "rock bottom", with 78% of those surveyed saying the mood of workers was either quite negative or extremely negative while nine out of 10 who were questioned said the further education (FE) sector is underfunded.

Chris Greenshields, chair of Unison's FE committee, said: "This survey is damning. It's no surprise that it's one bad story after another in FE and our sector urgently needs a shot in the arm with additional ring-fenced funding for staff to reverse the decline.

"Trust in management is at an all-time low. Ordinary staff are appalled at the large pay-offs that unaccountable senior managers have been paying themselves while Unison members are working harder and longer hours to try to maintain the quality of services they offered before the mergers and redundancies across the whole sector."

Mr Greenshields made the comments as Unison published a report which found the college sector is "undergoing radical change at a time of substantial budget cuts".

A total of 266 Unison members working at 16 colleges took part in a survey which suggested "this is having a severe impact of the services colleges provide and that staff are under enormous pressure as they attempt to deliver a high-quality service".

Scotland has 20 FE colleges compared to 37 in 2011, with the report stating real-terms funding had fallen by £53 million between 2011 and 2014, and staff numbers have fallen by 9.3% since 2011-12.

More than three-quarters (77%) of those surveyed are either doubtful or extremely doubtful college services will improve within the next year.

Meanwhile, 70% described trust in management as being "low", with the report stating: "It is clear from the responses to our survey that there is something very wrong in FE."

Workload pressures "leave many who responded feeling that they are unable to provide the level of services they once did," the report said.

"While the impact of cuts and job losses are identified by members as reasons for the problems they are experiencing trying to deliver services, the role of managers is also having a significant impact.

"Only 16% of staff felt that there was proper communication between management and staff during the merger process while over 60% did not.

"Just over half of members (52%) are satisfied or very satisfied with FE as a place to work - hardly a ringing endorsement."

In addition, 74% of those surveyed were either unsatisfied or very unsatisfied with their wages.

Mr Greenshields said: "College management and the Scottish Government need to listen to the staff.

"We are here to work with the Scottish Government to make that vital difference. But it is getting increasingly difficult."

Labour's opportunity spokesman Iain Gray said: "The SNP government has decimated Scotland's crucial college sector.

"Budgets have been slashed, there are 140,000 fewer students and thousands of staff have lost their jobs. Yet we are told again and again by ministers that everything is fine.

"This damning survey shows that Scotland's college sector is far from fine after eight years of SNP mismanagement."

"The time has come for the SNP to acknowledge the damage they have done and start reversing it."

Liberal Democrat education spokesman Liam McArthur said: "This damning report, which highlights the views of college lecturers and staff, does not make for good reading for the SNP government.

"It will confirm to many college students what they already know: that their college is struggling to cope with SNP demands.

"My concern is that the longer this continues, the harder it will be to repair the damage. Ministers must listen to the views of college staff. They must tell students what they are going to do to address the serious problems identified in this report."

A Scottish Government spokeswoman said: "We have seen huge progress on college reform and this government has pushed for national pay bargaining, to which most colleges are now signed up to reforms which were designed to give a sharper focus on helping young people into jobs and the skills our economy needs to grow.

"In each of the last three years, we have exceeded our target to maintain the number of full-time equivalent places and improved the learner experience.

"In 2013-14, colleges delivered record levels of student retention, successful completion and a 34% increase in students progressing from college to university with advanced standing since 2009-10."