Malaysia's top diplomat turned the screws on Aung San Suu Kyi at emergency talks in Myanmar on Monday, warning that an army crackdown on the Rohingya minority could spark a regional migrant crisis.
More than 27,000 Muslim Rohingya have fled northwestern Myanmar for Bangladesh since the start of November to escape a military counter-insurgency operation.
Myanmar's army says it is hunting militants behind deadly raids on police posts in October.
But Rohingya survivors have described rape, murder and arson at the hands of soldiers -- accounts that have raised global alarm and galvanised protests around Southeast Asia.
The exodus has sparked a rare dispute within the Association of Southeast Asian Nations (ASEAN), the 10-member bloc that prides itself on consensus diplomacy and non-interference.
On Monday ASEAN foreign ministers held talks in Yangon on the crisis.
Muslim-majority Malaysia called for an independent ASEAN-led investigation into the allegations of army abuse.
Foreign Minister Anifah Aman also urged full humanitarian access to the locked-down area, where more than 130,000 people have been without aid for two months.
He warned the crackdown could trigger a repeat of last year's boat crisis, when thousands of starving Rohingya were abandoned at sea by traffickers as they tried to flee southwards to Malaysia.
"We believe that the situation is now of a regional concern and should be resolved together," he told the meeting, according to a statement from Kuala Lumpur.
"Myanmar must do more in trying to address the root causes of this problem."
On Monday Amnesty International joined the condemnation, saying the army's "widespread and systematic attack on a civilian population" may amount to crimes against humanity.
Myanmar's more than one million Rohingya have been described as among the most persecuted people in the world.
More than 120,000 were driven by bloody sectarian clashes in 2012 into displacement camps, where they live in conditions many have likened to apartheid.
- New wave of anger -
The latest crackdown in Myanmar's Rakhine state has generated a fresh wave of public anger, particularly in Malaysia, where tens of thousands of Rohingya eke out lives as undocumented workers.
This month Malaysian Prime Minister Najib Razak accused Suu Kyi of allowing "genocide" on her watch -- an unusually strong rebuke by one ASEAN state of another.
Myanmar, which has vehemently denied the allegations of abuse, angrily summoned Malaysia's ambassador and banned its workers from going to the country.
Suu Kyi also held talks with mainly Muslim Indonesia this month after cancelling a visit following protests and an attempted attack on the Myanmar embassy.
At Monday's talks ministers warned of the risk of a "spillover effect on Myanmar's neighbours in terms of security and stability" from the Rakhine violence, a diplomat told AFP.
Ministers also took aim at Nobel laureate Suu Kyi for not doing more to rein in the military, which still has a quarter of parliament seats and controls key levers of power in her elected government.
"Her hands are tied because of the military, but she has to shoulder her responsibility as a leader of Myanmar," said the diplomat, who asked not to be named.
Suu Kyi has pleaded for time and international understanding over the incendiary issue.
The Rohingya are reviled in Buddhist-majority Myanmar, denied citizenship and widely tagged as "Bengalis" -- or illegal immigrants from Bangladesh.
In a statement after Monday's meeting Suu Kyi said talks were "candid and transparent" but also "emphasised the importance of strengthening ASEAN unity and resolving the differences between ASEAN family members".
Myanmar has faced a cascade of criticism from outside the region over the Rohingya crisis, including from the United States and the United Nations.
Last week, UN rights commissioner Zeid Ra'ad Al Hussein criticised the government's "callous" handling of the crisis, describing it as "a lesson in how to make a bad situation worse".