The ambulance service is in a "critical condition", with staff at breaking point, a new report has warned.

Research by Unison found ambulance staff are overworked and highly stressed, with many thinking of leaving the service.

Many workers have experienced violence and abuse, with six in ten saying they have suffered physical and/or verbal abuse at work, and three-quarters of women saying they have experienced it.

Almost all (98%) paramedics have experienced violence and/or abuse while working while 40% of patient transport staff have suffered it.

The union warned a lack of staff and resources is putting patients' health and, in some cases, lives at risk, and is also having an impact on the health and wellbeing of ambulance staff.

David O'Connor, Unison regional organiser, said: "This report reveals the immense pressure facing Scotland's ambulance staff. It shows a dedicated workforce who are working hard to support the public under enormous pressure.

"They feel exhausted, undervalued and suffer violence regularly. They are struggling to deal with the demands placed upon them. The service is already in critical condition with ambulance staff at breaking point and demand is continuing to grow.

"We need urgent action to increase funding and resources in order to deliver the high quality of care our patients rely on and deserve."

The survey found that, despite an increase in funding and staff numbers over the past five years, demand has increased far beyond those resources.

It also found demand is increasing by 4% per year, the equivalent of an extra 24,000 calls, but staffing levels are still too low to meet the increasing demand.

More than eight in ten ambulance staff (86%) overall reported that their workloads are heavier, rising to 98% among paramedics.

Almost three-quarters (74%) of respondents describe morale as poor or very poor while 25% rate their job as ten on a 1-10 stress scale.

Meanwhile four in ten workers often think about leaving the service, rising to 47% among paramedics.

Stevie Gilroy, Unison Scottish Ambulance Service branch secretary, said: "This report sends a stark warning to the Scottish Ambulance Service. Staff are struggling to keep up with the demands placed upon them and it's not just the staff that suffer, it's patients too.

"We're already at crisis point and we need urgent action to protect this vital service."

A spokesman for the Scottish Ambulance Service said: "Our staff do a fantastic job each and every day in Scotland's communities caring for patients and saving lives.

"Given how hard they work, and the situations they face, we recognise it can also be a stressful job, which is why we have a wide range of support mechanisms available to them and long-standing arrangements in place to ensure we balance their needs and wellbeing.

"With an expanding, ageing population, demand for ambulance services across the UK continues to grow but we are at the forefront of building our capacity so that we can continue to meet this demand, the needs of patients and our staff."

Scottish Labour said the report was "deeply troubling".

Health spokeswoman Monica Lennon said: "It's simply unacceptable that we face a situation where almost half of paramedics say they often think about leaving the service because they don't have the support they need.

"We urgently need to invest in the Scottish Ambulance Service to keep up with demand and ensure that staff have the equipment and resources they need to do their jobs."