Police will now have the power to conduct random weapons searches in designated public places without warning, scrapping the previous requirement to advertise seven days in advance.

Children under 18 will also be banned from being able to buy weapons.

Police and Emergency Services Minister Bob Cameron said the laws sent a strong message.

"Knives are not defensive weapons. They can lead to harm and people should not be carrying them around in the street thinking it's OK to do so – it is not," he said.

Footscray's Inspector Ian Geddes said laws on carrying knives should be strengthened. "You can have a firearm to go hunting if you are a licensed shooter, but you are still not allowed to carry your gun down the street. I think that is where we need to go with this piece of legislation as well."

In January, police conducted a random weapons search at Footscray railway station, confiscating 12 weapons.

On the day police searched 182

people and found seven carrying knuckledusters, a machete and knives.

Inspector Geddes said the search was a success and gave police a good idea of how many and what type of people were carrying weapons.

"We took a number of weapons off people that day. You've got seven people with weapons; that is seven people who can use weapons, that is seven potential victims."

But Western Metropolitan Greens MP Colleen Hartland said weapons searches were not effective.

"How much time and effort does it take for them to be able to mount what looked like PR exercises? The police don't need more powers, they need more resources. They should be dealing with the shortage of police."

As of last week, a Victoria Police spokesman could not confirm if any charges had been laid in relation to the January search. He said it would be up to magistrates whether the seized weapons would be destroyed or returned to their owners.