OPPOSITION Leader Tony Abbott says a coalition government will spend an extra $100 million on Customs to tackle the flow of illegal guns.

"An incoming coalition government will do our bit to crack down on gun crime right around Australia," he told reporters in western Sydney on Monday.

"The current government in losing control of our borders has not just failed to stop the boats but has failed to stop the guns as well."

Mr Abbott says the coalition will also support mandatory five-year jail sentences for the illegal importation of guns and work with states and territories to set up local anti-gang squads.

NSW Liberal Premier Barry O'Farrell called the commitments "terrific".

But Justice Minister Jason Clare says the illegal importation of guns is just a small part of the bigger problem of the number of illegal weapons in Australia.

"We've got a quarter of a million illegal weapons in the hands of criminals on the streets right now," Mr Clare told AAP on Monday while campaigning in the seat of Adelaide held by Labor's Kate Ellis.

"Most of those have been here a long time. They're either weapons that weren't handed in after the Port Arthur massacre or they're weapons that are stolen from legitimate owners."

Mr Clare says he's advocating for all states to implement firearm prohibition orders which already exists in South Australia.

That will give police the power to randomly search serious criminals for firearms.

"It exists here in South Australia and it's been very effective against outlaw motorcycle gangs. It's needed on the streets of western Sydney," he said.