The Association of Professional Ambulance Personnel (APAP), UK, has once again called for body armour for its members. Attacks on its members have continued to grow last year.
Figures obtained under the Freedom of Information Act show more than 500 incidents of violence and verbal abuse have been recorded in Wales since 2006.
Jonathan Fox, APAP spokesman, said: "Body armour would protect against kicking and punching, which crews face on a daily basis.
"Paramedics are being exposed to high risk situations in the same way that police officers are.
"Their lack of protection is undermining the effectiveness of the ambulance service."
In an interview to the BBC a couple of years ago, Jonathan Fox had warned escalating crime was increasing the risk of serious injury to the paramedics who responded to casualties.
He cited his own experience of treating a violent drug addict who had suffered an overdose.
Although he had no weapons, the man was lashing out and kicking Mr Fox who was fortunately wearing his body armour, which had been issued by the London Ambulance Trust in 2003, protecting him from harm.
Mr Fox said: "Although the majority of public we serve are fine, there is a disproportionate minority of people that we attend who can turn violent and it's this risk we are trying to address by reviewing this initiative."
There were 1,006 physical assaults against ambulance staff in England for the year 2006/7, figures show.
Matt Whitticombe, APAP's North West regional secretary, said: "While many of our highly-trained and dedicated staff at the cutting edge of the NHS face the threat of physical assault on a regular basis without this protection, our desk-bound administrators continue to prevaricate over the merits of body armour and so the dangers persist.
"Body armour is part of a package of safe systems, conflict-resolution strategies and personal protective equipment necessary to ensure a safer working environment for those who dedicate their working lives to the care of others."
He said there was reluctance to provide the vests, which are tailor-made to fit each specific uniform, because of concerns they are cumbersome and would encourage paramedics to take risks.
"That is unsubstantiated by the research that's been done in police officers, which shows they do not take more risks and assaults against them go down."
He added that the vests were lightweight.
A Department of Health spokesman had said then: "The government takes the safety of ambulance staff extremely seriously.
"Ambulance crews across the country can have stab vests if it is decided they are necessary by their local NHS trust.
"Any violence against NHS staff is unacceptable. That is why we have announced an extra Ģ97m for security and measures that will make the NHS a safer place to work, including mobile alarms connected to control rooms."