Myanmar's leader Aung San Suu Kyi has been "hung out to dry" over atrocities on Rohingya Muslims, according to a senior Australian Labor Party official and East Timor's former president Jose Ramos Horta.

"Condemning Suu Kyi, a former dissident and Nobel peace prize winner, for not using her position as a megaphone to address the problem may be emotionally satisfying but does not help those most in need," Janelle Saffin, a former federal MP and chair of Labor's International Party Development Committee, and Dr Ramos Horta wrote in a joint statement.

Mounting international criticism of Ms Suu Kyi "is obscuring the military's responsibility in the crisis", they wrote.

UN investigators have cited evidence of mass rapes, torture, the slaughter of babies and the burning of families alive by Myanmar security forces in the country's western Rakhine state, home to more than one million Rohingya.

But Ms Saffin and Dr Ramos Horta warned that a United Nations investigation into the atrocities that was approved last month "will not put an end to the violence and may even inflame an already volatile situation".

"No UN commission of inquiry can unpack this history," they wrote in the statement published by Project Syndicate.

The Turnbull government on March 26 co-sponsored a resolution at the UN Rights Commission in Geneva to send a fact-finding mission to Myanmar to investigate what the UN says could amount to "ethnic cleansing" and crimes against humanity.

Earlier foreign minister Julie Bishop told Ms Suu Kyi that Australia was "deeply concerned" about the atrocities documented in a UN report in February.

As international criticism of Ms Suu Kyi has grown since then, the 72-year-old, who formally holds the title State Counsellor, has denied any ethnic cleansing, while Myanmar's military has warned against the UN intervention and described Rohingya as "Bengali interlopers", despite them having lived in Rakhine for generations.

Dr Ramos Horta's defence of Ms Suu Kyi came four months after he co-signed a letter with more than a dozen other Nobel peace prize winners which criticised Ms Suu Kyi, saying "we are frustrated that she has not taken any initiative to ensure full and equal citizenship rights of the Rohingya".

The UN has described Rohingya in Buddhist-majority Myanmar as among the world's most persecuted people.

In the statement from Yangon, Ms Saffin, who has a long history of pushing for democracy in Myanmar, and Dr Ramos Horta said that "given that atrocities are still being committed it would be premature to excuse or defend any of Myanmar's leaders".

"But we should identify the right targets for criticism," they said. "Suu Kyi has been hung out to dry while Myanmar's generals – who misruled the country for decades – have been allowed to step back as the conflict escalates."

Ms Saffin and Dr Ramos Horta said Myanmar's generals "never intended to let a civilian government hold them to account", referring to elections in late 2015 which Ms Suu Kyi's National League for Democracy won in a landslide.

The election was hailed as ending half a century of brutal military dictatorship.

"It is simply wrong to say that Suu Kyi has done nothing in the face of the horrors being perpetrated in Rakhine," Ms Saffin and Dr Ramos Horta said.

"One must remember that Myanmar is undergoing a fragile political transition, under a constitution that gives the military a leading role in national politics, while constraining Suu Kyi," they said, adding the military's commander-in-chief, General Min Aung Hlaing, has little responsibility but far more power.

Ms Saffin and Dr Ramos Horta said the international community should help provide services and defend the rule of law in Rakhine.

Ms Suu Kyi has acknowledged disappointment over the state of her country 12 months after being swept into power on a wave of optimism, and said she is prepared to step down if people are dissatisfied with her leadership.