Victoria Police and AFP have also revealed they are uncovering more cases of trafficking that arerelated to forced marriages. Police have more than 20 active investigations into alleged forced marriages, with 18 cases involving women aged under 18. Superintendent Matt Warren said these "child bride" cases were "a signficicant concern" for the AFP and mostly involved ethnic communities where arranged marriage is "very entrenched". "We are talking about females being forced into marriage. They are vulnerable, they are young," Mr Warren said. Victoria Police detective superintendent Rod Jouning said forced marriages involved human trafficking and sexual assault and were grossly under-reported due to the fear felt by victims. "There has probably been a real concentration on the fact that human trafficking equates to sex trafficking. It is far bigger than that. Far bigger. The other areas that are not as obvious involve labour trafficking and trafficking for forced marriages.

"With the growing number of communities we have with pre-arranged marriages, that becomes an issue for us," Mr Jouning said. "It's really under-reported. It's only when we have the women who have the courage to stand up and say no, I don't want that. Or someone else sees it happening and gets concerned." Mr Jouning said labour trafficking in Victoria was happening in the agriculture and construction industries as well as in cafes. He said trafficked workers "get charged an enormous rate for a little room and enormous rates for food. So they end up working for just about nothing. There have been other occurrences where workers have been extorted for sexual favours with the threat that 'if you don't do that, we'll take away your visas'." The AFP believes the increase in cases of human trafficking is due to the police's focus on attacking trafficking syndicates and changes in laws that allow for the prosecution of those who arrange forced marriages.

But state and federal police warn that because of the fear and culture of silence confronting trafficking victims, it is likely many cases are never reported. Successful prosecutions for human trafficking remain difficult to achieve because victims are often reluctant witnesses. Victoria Police and the AFP are concentrating on disrupting syndicates, with some operations taking years due to the reluctance of witnesses to come forward. Last year, the AFP arrested members of a human trafficking syndicatesuspected of trafficking women into Victoria from Asia for a decade. Cancelling the legal brothel licences held by suspected traffickers who have not been charged or convicted also remains a challenge, with one prominent Asian brothel madam and alleged trafficking syndicate member, Lin Gao, still managing at least one Victorian brothel.

The head of Victoria Police's sex industry co-ordination unit, Marilynn Ross, is launching a campaign to educate state police about how to detect and act on warning signs that a person has been trafficked, including having false travel documents. "One of the ones we have really found is they [suspected victims] all have the same address and same story and they don't have a key at the place where they reside. People speak for them. So you start talking to someone and someone else will jump in and they will answer the questions [for them]," said Ms Ross, whose team this week shut down two illegal brothels in Melbourne's north as part of a continuing campaign cracking down on the state's 300 illegal venues. Mr Warren said: "Korean or Asian brothels in Melbourne and Sydney have consistently come to notice. "I think of it in terms of people being trafficked – there is no question that given the reluctance of victims to come forward in sex servitude or sexual slavery in the brothels … it is well under-reported. The problem is greater than we are seeing." Shakti Migration and Refugee Women's Support Group Melbourne has been working with police and other agencies since 2011 to enable vulnerable girls and women to break free from forced marriages and other forms of abuse.

Its service co-ordinator, Taeko Yamada, said victims of forced marriage could be as young as 12 and found it hard to come forward because the "prospect of ostracism and honour killing are very real". Loading "Also so many young girls and women do give in. Once a marital rape happens and they have children it becomes very hard to get out," Ms Yamada said. Shakti will open a crisis phone line next year. It also has a Sydney office.