Britain and Canada have already called for an international inquiry, saying Sri Lanka has failed to heed two previous UN resolutions for it to launch its own judicial inquiry and prosecutions. It is widely speculated that the US will present a resolution before the UNHRC demanding an international inquiry.

Asked by Australian media whether Australia would support a UN-sponsored investigation and would co-sponsor any resolution, Minister for Foreign Affairs Julie Bishop was non-committal.

"The Australian government has consistently urged Sri Lanka to ensure that all allegations of serious international crimes committed by both sides to the conflict are investigated and prosecuted in a transparent and independent manner," she said in a statement.

"Any future formal investigation would need to be agreed by the international community and would be a matter for relevant bodies at the time,” Australian media, quoting the Foreign Minister, said.