Preparations are under way to accommodate more asylum seekers at Christmas Island in case the Australian government loses a court case against offshore detention, Immigration Minister Peter Dutton says.
Lawyers have argued that detaining asylum seekers on Nauru is in breach of Australian laws.
They have told the High Court of Australia that the federal government is in control of the centre, despite it operating under Nauruan law.
Mr Dutton said he was confident the federal government was in a strong legal position.
He told Sky News the High Court was expected to deliver its finding next year, but the Department of Immigration and Border Protection had already started planning in case of a loss.
"It's prudent for my department ... to put in place contingency arrangements," he said.
"If we needed to accommodate more people on Christmas Island, there is some prep work that is taking place there now."
Further detail has been sought from the Department of Immigration and Border Protection.