Boat people returned to Christmas Island

Sydney's Villawood Detention Centre. Photo / Getty Images

Survivors of December's Christmas Island boat tragedy, flown to Sydney this week to attend funerals for those who died, have been returned to the island.

Refugee advocates say they were taken away from the Villawood detention centre in a shroud of secrecy.

The 22 survivors, including a nine-year-old orphaned boy, were housed at Villawood after attending funerals on Tuesday for those who died.

They had been due to leave the centre about 9am today.

Social Justice Network spokesman Jamal Daoud said family and well-wishers came to say goodbye to them about 8am, and it was disappointing they had been denied the opportunity to say goodbye to them.

It is still not known what time they left.

"This is very bad, because these people told them they wanted to say goodbye to their relatives and they were denied this right," Mr Daoud said.

The Department of Immigration and Citizenship confirmed the 22 people - including nine-year-old Iranian Senan - had left Villawood.

"Decisions on their long-term placement on the mainland will be made soon on a case by case basis," a spokesman told AAP.

Arguing they were not mentally fit to return to the island because it would bring up too many painful memories for them, refugee advocates filed a request with the Human Rights Commissioner this morning in the hope of allowing them to stay longer.

However, the detainees were secretly ushered away hours before 9am on a flight back to Christmas Island.

- AAP