There have been unconfirmed reports that a boat of 153 Tamil asylum seekers heading towards Christmas Island have been handed over to the Sri Lankan Navy by Australian authorities, reports the Guardian.

Christmas Island shire president, Gordon Thomson, spoke to Guardian Australia on Tuesday informing them of the latest reports, adding that there was no sign of the vessel at Chirstmas Island. Thomson told AAP,

"It's a very, very, very disturbing story, if it's true... That would be a quantum leap in ruthless bastardry by any government."

The Sri Lankan Navy denied that the asylum seekers, of which more than 30 are thought to be children, have been handed over to them by Australian authorities.

Speaking to ABC radio, Australian Prime Minister Tony Abbott refused to comment on whether the reports were true, saying "I'm not going to comment on the operational detail of what happens on the water."

Greens senator and immigration spokesperson Sarah Hanson-Young called the reports “extremely concerning” and added,

“The Australian government has a responsibility to assess these people’s claims for protection, not hand them over to the very authorities they are fleeing.”

“The minister must put an end to the rumours and tell the Australian people what is really going on… There are children on board these boats, we must ensure their safety and offer them protection.”

The Director of the Human Rights Legal centre Daniel Webb commented on the Australian government’s silence on the issue, saying,

"There are serious questions about whether our government is complying with domestic and international laws. The answers to those questions depend on the facts but our government won’t give us any.”

His statement was reiterated by the Refugee Council’s chief executive, Paul Power who said,

“As a Refugee Convention signatory, Australia has a clear obligation not to send asylum seekers back to danger without giving them a chance to put their case for refugee protection,”

Noting that Tamils face “persecution or worse” if they were to be returned to Sri Lanka, Power said,

“Forcing people seeking refugee protection back to their country of origin without properly investigating their claims is the most flagrant of all breaches of the Refugee Convention and international law.

“For asylum seekers, this is a matter of life and death, particularly in Sri Lanka which has a long history of political violence on a scale unimaginable to Australians.”