The Defence Department says it will investigate why a boat carrying asylum seekers sank in the Indian Ocean last night.
HMAS Wollongong responded to a distress call from the boat which was found south-east of Christmas Island.
Defence says the boat initially appeared to be in good condition and it was being escorted back to the island.
The Deputy Chief of Joint Operations, Rear Admiral Allan Du Toit, says the 16 women and children were transferred off the boat before it sank and the other passengers were rescued from the water.
“[They] are now safe with no apparent health issues,” he said.
“Rescue operations like this are always extremely difficult and the fact the rescue took place safely in the dark is a credit to all of those involved.”