Mr Watts said Armourguard was a member of the security association and was required to follow its code of practice.
"Our code says there must be a minimum hourly radio check for all guards, so I'd like to talk to Armourguard and find out what the situation with this guard was," he said.
Physical assaults on security staff were becoming more common.
"The number of assaults here is low compared to other countries, but it's on the rise," Mr Watts said.
"I'd say it's quite common for security guards to be assaulted, unfortunately."
In an ideal world, guards would work in pairs, but that was not financially viable for most security companies, he said.
However, the association was pushing for more licensing and regulation in the industry, which was one of the least regulated in the Western world.
Just last year, a minimum level of training was made mandatory for all security guards, and anyone employed as a security guard must go through two days of training, Mr Watts said.
"This doesn't include any physical training, but it does include first aid and conflict resolution."
Many security companies were investing in extra training for their staff, Mr Watts said.
"Before this, a security company could put anyone in a uniform and call them a security guard."
Armourguard general manager of manned services Mark O'Brien told the Wanganui Chronicle he could not discuss the situation fully.
"For the safety and security of Armourguard staff and the people and property we protect, we are unable to discuss in detail many of the policies and procedures we have in place," Mr O'Brien said.
"These are a private matter between Armourguard and our clients. Contrary to suggestions, the guard was not left unattended for hours."
A review of security procedures at Wanganui Hospital was under way, Mr O'Brien said.
"This is a standard undertaking whenever an incident of this nature occurs.
"Our full support continues to go to assisting the recovery of the staff member who was assaulted and the police who are working towards tracking down the offenders."