A manhunt is underway for Australia's top 20 fugitives, including men wanted over murders, drug trafficking and sex crimes.

Images of the most wanted men have been released as part of a nationwide police blitz called Operation Roam.

Last year three people were arrested within 48 hours of Operation Roam's launch and all up nine people were arrested.

People are asked to visit the Crime Stoppers website to see if they recognise anyone on the list and to report the information if they do.

The deputy chairman of Crime Stoppers Australia, Peter Price, said the wanted men have committed serious crimes in more than one state or territory.

"We need the help of the Australian public to locate them before they commit any further crimes and do more harm," he said.

Sam Hunter, the chief executive officer of Crime Stoppers Victoria, said the mobile nature of today's society means people often move around to evade capture.

"They may now be living in your neighbourhood," she said.

"They could be your neighbour or mechanic and have assumed another identity.

"They might catch the train in the morning."

The wanted men have committed a number of offences including drug trafficking, robbery, sexual assault and attempted murder.

One of them, Stuart Pearce from South Australia, is wanted for questioning over the alleged murder of his wife and three children at Parafield Gardens in South Australia in 1991.

"There's a $1 million reward offered by the South Australian Government for information leading to the arrest of the person who may have committed the murder," Ms Hunter said.

"He could be anywhere in the country.

"Any information that could be passed on to Crime Stoppers to help pass that again on to Victoria or South Australian police would be most valuable."

'We just need to know what you know'

Victoria Police Deputy Commissioner Tim Cartwright said there was "a wealth of untapped community information out there".

Even the smallest piece of information could be valuable and people do not have to reveal their identity to Crime Stoppers

"We just need to know what you know," Ms Hunter said.

"Every small piece of information helps police to build up an intelligence picture.

"Even if people think it may not be worth the call we urge you to give us a call. we'll pass that on to police and they can be the judge of how useful that information may be."

Crime Stoppers can be contacted at 1800 333 000 or visited at CrimeStoppers.com.au.