There is speculation a boatload of Tamil asylum seekers has been handed over to the Sri Lankan Navy as the federal government continues its silence over the reported interception of two vessels.
Christmas Island local councillor Gordon Thomson has called on the federal government to confirm the accuracy of reports that asylum seekers had been transferred from Australian custody.
"It's a very, very, very disturbing story, if it's true," he told AAP.
"That would be a quantum leap in ruthless bastardry by any government."
The government has repeatedly refused to confirm reports that two boats have been intercepted by Australian authorities off Christmas Island.
One of the boats is reportedly carrying 153 Tamil asylum seekers, including about 30 children - many of them sick - while the other has 50 people aboard.
Refugee advocates say they have not heard from the Tamil asylum seekers since Saturday and they believe Australia is coordinating with the Sri Lankan navy to tow them back.
Earlier on Tuesday, Prime Minister Tony Abbott refused to say whether the boat was being taken back to Sri Lanka.
"I'm not going to comment on the operational detail of what happens on the water," he told ABC Radio.
Australian Greens senator Sarah Hanson-Young said the reports were concerning.
She said the government had a responsibility to assess people's claims for protection and not hand them over to the very authorities they were fleeing.
A spokesman for the Sri Lankan military denied the reports.
"We are not aware of any arrangements of the Australian Navy handing over refugees, to Sri Lankan Navy," he told ABC Radio.
A spokesman for Immigration Minister Scott Morrison said responding to speculative claims was "contrary to the policy and practice of Operation Sovereign Borders".
