Prime Minister Tony Abbott is under pressure to join other Commonwealth leaders in raising human rights concerns with the Sri Lankan government.
Security is tight around hotels and conference venues ahead of Friday's opening of the Commonwealth Heads of Government Meeting in Colombo, with machine-gun wielding soldiers and police highly visible.
Mr Abbott will fly to Colombo on Thursday and address the summit on Friday.
The leaders of Canada, India and Mauritius have boycotted the gathering over claims the Sri Lankan regime's failing to properly investigate atrocities at the end of the three-decade long civil war and uphold basic rights such as freedom to speak and protest.
The Senate on Thursday passed a resolution calling on Mr Abbott to "raise the matter of an independent investigation into allegations of violations of international human rights law and international humanitarian law" with Sri Lankan president Mahinda Rajapaksa.
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British Foreign Minister William Hague told the BBC on Thursday Sri Lanka had put itself in the spotlight by hosting the summit and his government would use this "constructively ... to voice concerns and call for progress and accountability".
Mr Abbott said he did not know what action would be taken at CHOGM, but he was committed to human rights.
"Australia is an enthusiastic participant in all the international organisations to which we belong," he told Fairfax radio.
"The Commonwealth is an important association of a very diverse group of countries, but we have a commitment to the values, the best values, of the former British empire."
A Sri Lankan information ministry spokesman said the Commonwealth leaders had been invited to his country for CHOGM - not to raise issues with his government.
Journalists in Colombo have reported incidents of being followed or harassed by Sri Lankan security forces and the hotels are understood to be routinely passing on passport details to police.
Australian Greens senator Lee Rhiannon, who was detained in Sri Lanka last weekend, said she had found evidence of "ongoing abuses of human and legal rights" during her visit.
International civil rights groups say up to 40,000 civilians were killed and many more tortured or raped in the final months of fighting in 2009, but the Sri Lankan government disputes this.
Foreign Minister Julie Bishop is already in Colombo to meet with her Commonwealth colleagues.
She has held bilateral meetings with the foreign ministers of Britain, Sri Lanka, Kenya and Papua New Guinea as well as Caribbean community leaders.
