Giovanni "Johnny" Madafferi, 24, was arrested on June 4, after police officers conducted a random breath test in Broadmeadows and discovered he was driving a stolen hire car.

A search of the black Toyota Corolla uncovered a gun and knife.

A Victoria Police spokeswoman confirmed Mr Madafferi has been charged with theft of a motor vehicle, possessing a firearm and a prohibited weapon (knife), and receiving stolen goods. He will appear before the Broadmeadows Magistrates' Court on August 12.

Mr Madafferi is one of  the four children of Francesco "Frank" Madafferi, 54, who was granted an Australian visa by former Liberal immigration minister Amanda Vanstone in 2005 after intense lobbying and political donations, revealed by a recent Fairfax Media/Four Corners investigation.

The reversal of a previous order to deport Madafferi to Italy – where he has convictions for extortion, drugs and weapons offences – is believed to have been made because it would have unfairly affected his wife and children.

But within two years of the reprieve, Madafferi was charged over his role in the importation of 15 million ecstasy tablets, and received a 10-year prison sentence.

Johnny Madafferi's arrest  by the Hume Crime Investigation Unit follows a Fairfax Media report that revealed police are discovering guns in cars every two days in Melbourne's north-west.

The region, which includes Broadmeadows, Sunshine and Werribee, also recorded a firearms offence such as a drive-by shooting every six days, amid concerns of a growing "gangster culture" among young men in the area.

Crime Statistics Agency figures released last month revealed an almost threefold increase in firearms offences in the north-west region during the past five years, from 581 in the year to March 2011, to 1332 in the 12 months to April 2015.

Victorian Police Minister Wade Noonan has announced a tightening of gun-trafficking legislation and a widening of police powers in response to the rise in weapons seizures and shootings.