More Australians are dying from accidental opioid overdoses each year, with prescription painkillers rather than heroin now accounting for two-thirds of the fatalities, latest Australian Bureau of Statistics data shows.

An analysis of finalised ABS data by researchers at the National Drug and Alcohol Research Centre found 68 per cent of the 668 overdose deaths in 2013 were related to pharmaceutical opioids – a far cry from the heroin epidemic of the 1990s when the majority of opioid deaths were caused by illicit drugs.

The death rate has more than doubled among addicts aged between 35 and 44 since 2007. The death toll is expected to rise.

"We expect further increases once the deaths data for 2014 and 2015 are finalised," said lead author Amanda Roxburgh.