Federal police are investigating a record number of human trafficking cases involving sex slavery, forced marriages and child brides. The number of active investigations into human trafficking has doubled in the past two years to 60. Police said trafficking crimes are grossly under-reported. The Victorian police force is urging its officers across the state to be on the alert in cafes, on farms and in the construction industry. Police are also examining whether some Melbourne karaoke bars are hosting trafficked women or operating as illegal brothels, which would add to the estimated 300 illegal brothels already operating across the city. Police are also uncovering more cases of trafficking related to forced marriages and have 20+ active investigations into alleged forced marriages.