SYDNEY (AGENCE FRANCE-PRESSE) - A Myanmar asylum-seeker was Thursday (Sept 21) sentenced to 18 months behind bars for marrying an underage girl in Australia in what is believed to be the nation's first such prosecution.

The man wedded the 14-year-old at an Islamic mosque in the Melbourne suburb of Noble Park in September last year when he was 34.

Parts of the ceremony were recorded and found on his mobile phone, the Victoria County Court was told, with the man giving the girl's mother gold jewellery worth A$1,480 (S$1,600) as a dowry.

"To say that you come from a culture permissive of child marriage carries no weight and provides no mitigation as regards your offending," judge Lisa Hannan said at the sentencing hearing.

"While religious tolerance and a firm embracement of multiculturalism are cornerstones of Australian society, it is not mitigatory to say your conduct was permitted within the rules of Islam or any other religion or belief system.

"What you did was legally wrong and morally indefensible. The victim was entitled to a childhood you took from her."

The man cannot be identified to protect the girl's identity.

Judge Hannan sentenced him to 18 months' jail, but due to time already served he would be freed in 13 days and sent to immigration detention as his bridging visa was cancelled.

He will remain there unless issued another visa as he had been deemed stateless, she added.

The man pleaded guilty to the offence, which carries a maximum penalty of five years in prison.

Australia in 2013 outlawed forced marriages, deemed as when a person had been coerced or threatened into the union, or is incapable of understanding such a ceremony due to their age or mental capacity.

Between March 2013 and December 31 last year, police received 138 referrals for suspected forced marriage cases.

A person has to be at least 18 to wed in Australia, unless a court has approved a union where one party is aged between 16 and 18.