A new police unit dedicated to investigating sexual assaults on public transport has been created in Victoria in response to a dramatic increase in attacks.

The new unit in the transit safety division will look more closely into incidents including assault, obscene exposure and upskirting that are increasing on trams, trains and buses around Melbourne.

Authorities will also release the details of 20 unsolved assaults as part of the new Hands Off campaign, aimed at cracking down on behaviour and identifying more offenders.

The 20 cases are just some of the 350 sexual offences reported on public transport over the past 12 months — up from 249 the previous year.

Today authorities released the pictures of several men wanted in relation to a number of incidents.

Police hope the campaign will help identify a number of suspects. ( Supplied: Victoria Police )

Cathy Rhodes from Crime Stoppers urged people with information to speak out.

"People committing this type of abhorrent offending on our public transport system must be held accountable for these crimes," she said.

"We're asking the community to review these images and share them far and wide."

Victoria Police Transit Safety Division Inspector Karl Curran said the organisation would establish a new team to look specifically at sexual offences on public transport.

"Obviously they [suspects] feel that offending against a person in a vulnerable position means they will get away with it," he said.

"What we're doing is relaying some resources for a dedicated team to investigate these offences [because] we're concerned about the increase in numbers."

There are more than 1.6 million passenger trips made per day in Victoria, and on average one sexual offence is reported.

Public Transport Victoria chief executive Jeroen Weimer said while the system was "overwhelmingly safe", the organisation was determined to stamp out the problem.

"We have hundreds of thousands of staff across our network, we have over 9,000 CCTV cameras," he said.

"We want to highlight that we will not tolerate this behaviour and that these are the kinds of images we have to make sure people are brought to justice."