Victorian police will be given new powers to secretly search homes - for crimes that could include theft and minor assaults - if the Napthine government is re-elected.

Lawyers have criticised an exposure draft for a new state government bill to overhaul criminal investigation powers, saying they will lead to more children as young as 10 being fingerprinted.

Under the proposal, quietly released by the state government this week, the threshold for obtaining fingerprints and DNA samples would be reduced.

Fingerprints and DNA samples would be able to be obtained from people "suspected" on reasonable grounds to have committed a relevant offence, rather than the current threshold of "believed" to have committed an offence.

And covert search warrants - allowing police to secretly search premises - could be issued for indictable offences carrying a maximum penalty of 10 years imprisonment or more. They are currently reserved for only terrorism-related offences.

Australian Lawyers Alliance spokesman and barrister Greg Barns said the Coalition's proposal would lead to an increase in arrests and profiling, and more 10 to 14-year-olds would have their fingerprints stored on a national database.

"A 10-year-old's involvement in the criminal justice system should be kept to a minimum. If police can round up a kid on the basis that they have a suspicion they might be able to commit an offence, it becomes very problematic."

He said the exposure draft released by the Napthine government had no policy justification.

Covert warrants were often abused in Australia, he said, because there is not a strongly enforceable right to privacy.

"They are very hard to monitor and there is very little form of redress. They are under the radar."

Co-chair of the Law Institute of Victoria's criminal law section, Sam Norton, said the proposed expansion of covert search powers trampled on the privacy of Victorians.

"They have previously only been reserved for terrorist-related offences. Now it would apply to offences with a maximum penalty of 10 years. Bear in mind that theft has a maximum penalty of 10 years. This is a massive broadening of those powers."

He said there needed to be rigorous oversight of covert search warrants.

The exposure draft released by the government said covert search warrants may only be issued where a police officer of Inspector rank or abobe authorises the application. Courts must also consider whether it is necessary for the premises to be searched without the occupiers knowledge.

It is understood the government anticipates that lowering the threshold for taking DNA and fingerprints will not disproportionately affect any age group.

Attorney-General Robert Clark said the proposed bill would ensure Victoria Police had the powers they needed to protect Victorians.

"Simplifying and updating these laws will also provide greater clarity and certainty about the law both for police and for those being investigated."

He said the threshold of reasonable suspicion was consistent with other jurisdictions.

In a separate proposal released by the Coalition on Wednesday, serious under-age offenders would have their criminal record made public if they were later jailed as an adult.

In a law and order election pitch by the Victorian government, serious crimes committed by youths including murder, sexual offences and armed robbery would be made public if the youth reoffends as an adult.

The law change would apply to offences committed on or after January 1, 2005, and would lift the prohibition restricting the publication of under-age offences.

Attorney-General Robert Clark said the current restrictions were designed to allow a young offender the opportunity to turn away from crime without having it on the public record for the rest of their lives.

But he said those who reoffend as adults "forfeited the opportunity they were given and the community is entitled to know the full picture about their serious criminal record".

"Adults who commit serious crimes should no longer be entitled to have their past crimes hidden from the public," he said.

-with Tom Cowie