Triple zero operators made several errors that may have contributed to delays in getting help for the eight people who died in Melbourne’s thunderstorm asthma disaster, a new report reveals.

In one asthma case that led to a death, a family was told an ambulance was on its way, but in fact it was not dispatched for another 18 minutes.

In another case, a triple zero call-taker did not stay on the phone to guide a family through first aid because the operator did not realise the severity of the situation.

In a third case, the priority of the emergency call was automatically downgraded.

In severalincidents in which people died, callers were on hold for more than two minutes. Triple zero calls are meant to be answered within five seconds.