Police are hoping to charge more people over the marriage of a 12-year-old girl in the Hunter region.

A Muslim cleric, Riaz Tasawar who was until recently the imam at the Mayfield mosque in Newcastle, has been arrested over the illegal union.

The imam is accused of conducting the marriage of a girl who is now 13 to a 26-year-old man last month.

He has been granted bail to face court in April on a charge of solemnisation of a marriage by an unauthorised person.

The illegal union was sanctioned by the girl's father.

It is understood police are considering whether they can charge him.

Deputy Commissioner Nick Kaldas says police need to get legal advice before they can make more arrests

"The investigation is nowhere near finished. Any further charges that can be laid will be laid, possibly subject to legal advice," he said.

The 26-year-old who married the girl is in custody on child sex charges.

He is planning to apply for bail in court tomorrow.

The Islamic Centre of Newcastle has distanced itself from the former imam.

In a statement it says it had no knowledge of and did not give permission for the illegal marriage.

It says "what is most important at this point is for police to conclude their investigation and arrest all those responsible."

The Centre says it is assisting police with their investigation.