Suu Kyi was due to give a speech at Sydney's Lowy Institute on Tuesday but the institute said she had been forced to cancel as she was "not feeling well."
Suu Kyi had been scheduled to give a speech and answer questions at a foreign policy think-tank event in Sydney on Tuesday but cancelled because she was not feeling well, event organisers said, without giving more details.
Suu Kyi's spokesman Zaw Htay declined comment and referred questions to the Myanmar embassy in Canberra. A Reuters call to the embassy went unanswered.
Myanmar leader Aung San Suu Kyi's was feted in Australia on Monday with a military honour guard and 19-gun salute as part of a state visit that has provoked protests over her response to her country's violent campaign against Rohingya Muslims.
Suu Kyi arrived in Sydney over the weekend for a summit of Southeast Asian leaders and her state visit officially began on Monday as she was welcomed to Parliament House in Canberra. Her visit comes as she faces international criticism over what has become Asia's worst refugee crisis in decades.
More than 700,000 Rohingya have fled from Buddhist-majority Myanmar to neighboring Bangladesh since August, when the military responded to insurgent attacks on police with a clearance operation that the UN has described as ethnic cleansing. The campaign has included the burning of Rohingya villages, systematic rape, shootings and other rights violations.
There was no press conference with Australian Prime Minister Malcolm Turnbull or any public comment from Suu Kyi during her brief visit to the national capital on Monday. She had meetings with the prime minister and opposition leader.
Turnbull said on Sunday that Suu Kyi had used the weekend summit to seek humanitarian help from her fellow members of the Association of Southeast Asian Nations and Australia to deal with the crisis.
Malaysian Prime Minister Najib Razak told the summit the refugee crisis was no longer solely a domestic issue for Myanmar, as fleeing Rohingya could be prime targets for terrorist radicalisation.
Myanmar staunchly denies that its security forces have targeted Rohingya civilians and Suu Kyi has bristled at the international criticism.
But Myanmar's denials have appeared increasingly tenuous as horrific accounts from refugees have accumulated and satellite imagery and other evidence of destroyed Rohingya villages have been assembled.
The Associated Press last month documented through video and witness accounts at least five mass graves of Rohingya civilians. Witnesses said the military used acid to erase the identity of victims. The government denied it, maintaining that only "terrorists" were killed and then "carefully buried."
Suu Kyi, a Nobel Peace laureate, was a longtime political prisoner of Myanmar's former junta and frequently called for international intervention in her country during her almost 15 years under house arrest. She was released in 2010 and last visited Canberra in 2013 on an Australian tour, before she was allowed to stand for an election that her party eventually won in a landslide.
Then-Prime Minister Tony Abbott described her as an "icon of democracy" as he stood by her side at a joint press conference. Foreign Minister Julie Bishop said Suu Kyi had inspired her to enter politics.
Suu Kyi's global image has since taken a battering. She has seen several international honours she was given in the past revoked. Several fellow peace prize winners have publicly condemned her.
Military veto power
Though Suu Kyi has been the de facto head of Myanmar's civilian government since her party took power, she is limited in her control of the country by a constitution written by the outgoing junta. The military has effective veto power over all legislation and controls key ministries, including those overseeing security and defence.
The military is in charge of operations involving the Rohingya and ending them is not up to Suu Kyi.
Yet even when Suu Kyi has spoken on the issue, she has drawn criticism. In a September speech, her first public comments on the crisis, she asked for patience from the international community and suggested the refugees were partly responsible.
Suu Kyi faces a potential domestic backlash if she speaks on behalf of the Rohingya, who have been the target of anti-Muslim rhetoric. Many people agree with the official government stance that there is no such ethnicity as Rohingya and that those in the country have illegally migrated from Bangladesh.
Myanmar's backers globally have also had to tread carefully, not wanting to undermine Suu Kyi's weak civilian government at a time when the country is just emerging from decades of authoritarian rule.
Unlike the United Nations, United States and Britain, Australia has not accused Myanmar of "ethnic cleansing" or "crimes against humanity."
But Australia did support a United Nations resolution in December condemning the "very likely commission of crimes against humanity" by Myanmar security forces against Rohingya.
Human rights groups have criticised Australia for maintaining its limited military engagement with Myanmar. Australia provides English-language lessons and training courses to Myanmar officers to "promote professionalism and adherence to international laws" according to the defence department.
But Australia maintains a long-standing arms embargo with Myanmar.