Less than a fortnight before the Commonwealth Heads of Government Meeting (CHOGM) in Perth, there are calls for the Commonwealth to suspend or even throw Sri Lanka out of the organisation.

The Australian Federal Police (AFP) has confirmed it is considering whether there is sufficient evidence for a war crimes investigation against the country's top diplomat in Australia - former Sri Lankan navy chief Thisara Samarasinghe.

In a statement, the AFP confirmed it had received a submission compiled by the International Commission of Jurists, a legal rights lobby group composed of respected legal figures.

The allegation is that Mr Samarasinghe, a former admiral, was in charge of navy ships that fired on unarmed civilians as they fled the fighting in the final stages of the civil war.

He says there is no truth in the allegation.

Meena Krishnamurthy, who went to Sri Lanka seven years ago and fell in love with a Tamil man she says worked as an accountant with the rebel movement, says she witnessed a massacre.

From January 2009 the pair joined other Tamils fleeing the fighting in the north-east.

Sorry, this audio has expired AFP consider war crimes investigation against Sri Lankan dipomat ( Peter Lloyd )

As the Sri Lankan government surrounded and overran the Tamil Tiger movement, Ms Krishnamurthy says she witnessed the Sri Lankan navy firing at civilians onshore.

"I really want Australians to understand that I saw a massacre of people so recent," she said.

From the battlefield have come video recordings and written testimony from survivors like Ms Krishnamurthy, accusing the Sri Lankan forces of crimes against humanity, mostly based on the central accusation that innocent, non-combatant Tamil men, women and children mixing with fleeing Tamil soldiers were herded onto slivers of coastal territory and shelled into oblivion.

The accusation against Mr Samarasinghe raises the question of accountability.

There is no evidence that he was directly involved in shelling civilians nor is anyone yet claiming that he gave direct orders to that effect.

But the submission to the AFP reportedly does say that Mr Samarasinghe, as a military commander, holds what is referred to as "command responsibility" for the actions of his subordinates.

In January he resigned his commission to take up his diplomatic posting in Canberra.

"I specifically reject, totally reject such allegations. Such allegations are baseless," Mr Samarasinghe told the ABC.

'Moral obligation'

International law professor Donald Rothwell from the Australian National University says the AFP has the power to investigate.

"The Australian Federal Police have capacity under the Commonwealth Crimes Act and related legislation giving effect to the Geneva conventions which would allow the AFP to conduct investigations into the Commission of War Crimes that have occurred overseas, including crimes against humanity by any person including non-Australian citizens," he said.

He says the Government has a moral obligation to investigate.

"The incentive is that Australia is a party to the Rome Statute of the International Criminal Court. That statute does create certain obligations for Australia to conduct these types of investigations, and indeed I think there's a very strong argument that Australia both legally and morally needs to do so," he said.

For the matter to go any further, the AFP would have to prepare a brief of evidence for the Commonwealth Director of Public Prosecutions (DPP). It is then the DPP's call on whether to press a charge.

But there is just one problem - Mr Samarasinghe enjoys diplomatic immunity, which can only be revoked by the Sri Lankan government.

The front page news of the Commission of Jurists' submission comes just before CHOGM in Perth. Sri Lanka's president will be among those attending.

The submission reportedly calls for investigations into president Mahinda Rajapaksa, who is commander-in-chief of Sri Lanka's armed forces.

'Suspend Sri Lanka'

The end of the civil war created a humanitarian crisis. ( Sri Lanka Defence Ministry: AFP )

The president of the Australian section of the International Commission of Jurists, former New South Wales attorney-general John Dowd, says it is a matter of human rights.

"If the Commonwealth is to mean anything at all on issues like human rights, it has to look to the actions of its members. This is one of its members who's the putative next host in 2013," he said.

Mr Dowd says Sri Lanka should be suspended from the meeting.

"Well they should, I think, suspend it from the Councils of the Commonwealth until Sri Lanka does something about a war crimes tribunal and the other recommendations of the expert panel committee," he said.

"And if it does continue to do nothing it has to look at suspending Sri Lanka from the Commonwealth because they've done it to other countries for offences less than war crimes."

Last month the Swiss attorney-general announced plans to investigate allegations that Sri Lanka's second most senior diplomat to Switzerland and Germany was involved in war crimes.

Former general Jagath Dias was accused of ordering his troops to fire on civilians and hospital targets during the final offensive against the Tamil Tigers. The general was recalled to Colombo.

Tamils in Australia are hoping for something similar to happen here.