A 41-year-old man has been arrested at a Melbourne shopping centre after allegedly approaching teenagers and asking them for urine samples, claiming he needed them to pass a workplace drug test.

But the situation escalated dramatically when police searched the man, allegedly discovering a loaded firearm hidden down his pants, which immediately saw serious safety concerns in the busy shopping precinct.

WATCH THE VIDEO ABOVE: Man arrested after asking teens for urine samples

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Officers responded to Highpoint Shopping Centre in Maribyrnong on Monday afternoon following reports of the man’s unusual behaviour towards young people inside the complex.

The 41-year-old was taken into custody and police launched further investigations, executing search warrants at his Maidstone home on Tuesday.

The Maidstone man has been charged with prohibited person possess firearm, carry loaded firearm in public place, possess loaded firearm in public place and possess ammunition without licence.

He will face Melbourne Magistrates Court on Tuesday.

A man has been arrested at Highpoint Shopping Centre after allegedly asking teens for urine samples. Credit: 7NEWS