A nine-year-old girl has allegedly been involved in a case of forced marriage.

The Australian Federal Police are investigating the allegations, adding to the other 33 other cases they are looking into across the country since forced marriages were criminalised in 2013.

In the past 12 months, a total of 28 referrals have been received by AFP and 21 have been further investigated, according to a statement provided to Daily Mail Australia.

Scroll down for video

A nine-year-old girl has allegedly been forced into marriage. This is one of 34 cases AFP are investigating

Out of the 42 reports police had received from the community about suspected cases of forced marriages, they had whittled them down to 34 to pursue further.

Almost 30 of the cases had been involved a child under 18 years of age.

An AFP spokeswoman confirmed officers were looking into the suspected case of the nine-year-old but no more information could be provided as investigations were ongoing.

'The AFP received a referral in relation to the nine-year-old related to an allegation of forced marriage of a female,' she told Daily Mail Australia via an email statement.

'These allegations have not been able to be substantiated at this stage.'

If found guilty of a forced marriage offence, a person can served up to four years' imprisonment or seven years for a more serious case, according to the federal Attorney General's department.

Out of the 42 reports police had received from the community about suspected cases of forced marriages, they had whittled it down to 34 to pursue further

A more serious case would involve a victim who is under the age of 18.

But an offender could face up to 25 years' jail if the victim is under the age of 18 and taken overseas for the purpose of a forced marriage.

This latest suspected case of forced marriage is the second involving a nine-year-old girl in six months.

Last December The Immigrant Women's Health Service in Sydney raised the alarm when they received reports a girl had been flown to the Middle East to be married, the ABC reported.

Two months before that, a man accused of 'marrying' and having a sexual relationship with a 12-year-old girl, pleaded guilty to ongoing child sex abuse.

The 27-year-old Lebanese student, who cannot be named, pleaded guilty in Burwood Local Court in October to one count of persistent sexual abuse of a child.

The charge takes in 25 counts of sexual intercourse with a child between 10 and 14, with which the man was originally charged.

He has been ordered not to contact his victim for two years, and a date for sentencing will be decided next week.