THE NSW government says it will launch an inquiry into a glitch that shut down the paramedic computer dispatch system.

Ambulance of NSW's system was infected with a virus about 1pm on Saturday. Health officials had to revert to co-ordinating paramedics and ambulances via a manual paper-based system.

The opposition health spokeswoman, Jillian Skinner, said the glitch ''could potentially cost lives''. ''There's been a complete failure of the computer-aided dispatch system that allows ambulances to respond, sometimes to critically ill patients.''

Health Minister Carmel Tebbutt said she had been advised that no lives had been put at risk. ''Of course we will launch an inquiry once the system is back up and running.''

The general manager of operations for Ambulance of NSW, Mike Willis, said the computer system would not operate until technicians were sure the virus had been removed. He was unaware of any delays to triple-zero calls or any ''adverse patient outcomes''.

''It's important to note that at no time during that shutdown procedure were any triple-zero calls or in fact the integrity of our operation breached,'' he said. ''We're still taking calls and dispatching ambulances [albeit manually].''

AAP