An Iranian boy orphaned during the Christmas Island boat tragedy has arrived back in Sydney after being released from immigration detention.

Nine-year-old Seena Aklashi Sheikhdost was one of 22 survivors from the asylum seeker boat that broke apart off Christmas Island on December 15, killing up to 50 people.

Seena's mother, father and brother all died in the shipwreck tragedy. The distraught boy attended his father's funeral in Sydney last week, but the bodies of his mother and brother have never been found.

After the funeral, he was returned to the Christmas Island detention centre.

But after the threat of court action by human rights lawyers and many public calls for him to stay in NSW with his extended family, Immigration Minister Chris Bowen gave Seena permission to return to Sydney, and he was flown into RAAF Richmond last night.

His Sydney-based cousin, Jaffar Al-Ghbar, says Seena will receive medical treatment and attend a local school when he is ready.

"We are happy that Seena's back. He's going to be next to us with a loving family," he said.

"He needs to be treated by doctors, be taken to school, and do all the normal things that other kids do," he said.

Mr Al-Ghbar said he was grateful to Mr Bowen for letting Seena return to Sydney, where he will be re-united with his cousin and other relatives.

Another 13 detainees arrived on the same flight and will be placed in community detention, but refugee advocate Ian Rintoul says all survivors of the tragedy should be released into community care.

"They've lost children, they've lost partners, they should really be brought off Christmas Island as well," he said.

- ABC/AAP