A 17-year-old Kiwi teen held at an adult detention centre in Melbourne for months has been freed following criticism by New Zealand's government.

The teen has been held at the Melbourne Immigration Transit Accommodation facility since March, awaiting a deportation hearing this month.

He was being held over what's reported as non-violent offending

MFAT has released a statement confirming he's been released.

He's understood to be returning to family in Sydney.

The decision comes after acting prime minister, Winston Peters, accused Australia of breaching UN conventions on children's rights for holding the boy with adults.