Until 1 May South Wales traffic police patrolled the M4 all day every day
Four months after South Wales Police stopped patrolling the M4, civilian traffic officers to deal with motorway accidents have yet to be recruited.
The South Wales Police Federation argues that death and serious injury may increase as a result.
The Welsh Assembly Government says this is purely a matter for the South Wales and Gwent Police who are responsible.
Opposition parties say they are astonished that a new civilian traffic officer system is not yet in place.
The Secretary of the South Wales Police Federation says death and serious injury on the M4 are likely to increase because the force no longer patrols it.
Speaking to BBC Wales' The Politics Show, Wayne Baker said "political wrangling" over police funding has compromised public safety and left Wales more vulnerable to the importation of drugs and to terrorist threats.
I think undoubtedly we will see an increase in the number of collisions. If the speed increases because enforcement is no longer there then the likelihood of death on our motorways increases.
Wayne Baker, South Wales Police Federation
Until 1 May, South Wales traffic police patrolled the M4 all day every day.
Such patrols were withdrawn when South Wales Police didn't get the increase in the funding from council tax which its chief constable had asked for.
An assembly government trial of civilian traffic officers to replace them won't get going until the end of the year.
Mr Baker said: "I think undoubtedly we will see an increase in the number of collisions. If the speed increases because enforcement is no longer there then the likelihood of death on our motorways increases.
"It increases exponentially with the increase in the speed that we see. So in that sense the likelihood of further carnage on our motorways is increased.
There are fears there will be more collisions as a result
"Public safety has been compromised by the political wrangling between the chief officer in the South Wales Police force, who, quite justifiably I think, was asking for a small increase in the precept, and the political pressure that was applied then to prevent that from happening."
Traffic officers still attend the motorway when called to emergencies.
Acting Sergeant Steve Oaten of South Wales Police said: "I think the public are being short-changed to a certain extent.
"I think the standard of driving has declined to a certain extent over the short period that we haven't been policing it.
"And there's an obvious danger now from members of the public exceeding the speed limit or using a mobile phone.
"The odds of them being detected are negligible so they're going to continue to do that."
A Welsh Assembly Government spokesperson said: "South Wales and Gwent Police are legally responsible for policing the M4 in South Wales.
"Policing is a matter for the Home Office. We continue to work closely with the police to ensure traffic incidents are dealt with and ensure the safety of drivers.
It is not acceptable not to have a fully worked out, fully coordinated system in place before South Wales Police withdraw their policing
Jenny Randerson, Welsh Liberal Democrats
"We will shortly be launching a trial of traffic officers on the M4, to assist the police in their duties. It is intended that this trial service will be in place at the end of this year, following recruitment and training of the required personnel.
"These traffic officers will be given powers to deal with routine incidents, like vehicle breakdowns, which can cause congestion. This will free up the police to concentrate on law enforcement duties.
"It is not intended that Traffic Officers replace police patrols."
The spokesperson added that there were interim arrangements in place, and that these included: "Doubling our patrols of the motorway and entering into agreement with the south Wales police authorities to respond to any incidents that require further support. This has worked well."
Cardiff Central AM Jenny Randerson said she was astonished that full system to replace police patrols wasn't already up and running.
Jenny Randerson said: "I can understand why there is this crisis because of course the decision was made very suddenly as a result of the funding crisis facing South Wales Police but it is not acceptable not to have a fully worked out, fully coordinated system in place before South Wales Police withdraw their policing."
The civilian patrols won't have criminal enforcement powers. Its claimed this makes Wales more vulnerable to terrorist movements and to the importation of drugs from London and Bristol.
South Wales Police no longer patrol its section of the M4
Wayne Baker said: "These drugs are ending up in our communities. And they're coming in, very often, down the M4. And the M4 is the one place I can think of where the chief officer said, 'We will not routinely police'.
"So if you're a drug mule and you're carrying drugs, which is the area you would go to? Surely it's the area that's not being routinely policed."
Assistant Chief Constable Nick Croft, of South Wales Police, said: "Public safety has not been compromised as officers still attend incidents on the M4 whether it is to deal with an emergency or deal with criminals using the roads.
"We can reassure the public, and warn criminals, that the M4 is used throughout the day by officers travelling from one part of the force to another and they will deal with incidents as and when they arise. If there is specific intelligence in relation to criminality then we will act immediately."