The number of paramedic shifts unfilled in the Loddon Mallee region rose last year to 462 shifts, up from 307 in 2011, according to Ambulance Victoria documents.

Bendigo paramedic Brett Adie said the problem with rostering wasn't a new issue but it had been compounded by a centralised rostering system.

He said the control over rosters had been taken away from local stations about 18 months ago and was being redirected to staff in Ballarat and Melbourne.

"It's being poorly managed," he said. "There are instances where people don't know if they're working, or people saying they're available and the shift still goes unfilled. We've had trucks off the road because they couldn't find anyone."

Mr Adie said in some cases paramedics had driven up from Geelong to do a shift in Bendigo, despite someone in Bendigo being available.

Mr Adie said the problem in Bendigo had become more noticeable in the past 12 months, with a rising level of sick leave compounding the problem.

"I think the cause is that morale is at an all-time low," he said.

Labor's parliamentary secretary for health Wade Noonan said the number of unfilled shifts highlighted the dangers of not having a clear rostering system.

"Every time a shift goes unfilled, people living across the Loddon Mallee region are left dangerously exposed and entire communities are left without any ambulance cover, which is placing lives at risk," he said.

Mr Noonan said a recent report by the Auditor-General highlighted concerns about the centralisation of rostering arrangements.

It also stated that team managers had reported the policy had contributed to the problem of managing unplanned leave in regional and rural Victoria.

Ambulance Victoria Loddon Malle Regional Manager Kevin Masci defended the rostering system, saying almost 99 per cent of shifts were operated as scheduled.

"Paramedics obviously have a choice in what they do when they're off duty and if no one volunteers for that overtime shift, it is unfortunately unable to be filled," he said.

"Each day we roster over 620 shifts and to put this in perspective, each year we roster more than 240,000 shifts."

Across the state there were 2,939 shifts left unfilled by Ambulance Victoria in 2012.