Yangon - Myanmar's government lashed out at Malaysian Prime Minister Najib Razak on Friday, accusing him of using the Rohingya crisis unfolding in Rakhine state for his own "political interests".
The premier of Muslim-majority Malaysia has been a vocal critic of Myanmar since violence erupted in the north of the state in October, when the army started hunting attackers behind deadly raids on police border posts.
Since then at least 66,000 Rohingya have fled to neighbouring Bangladesh alleging security forces are carrying out a campaign of rape, torture and mass killings that Najib has said amounts to "genocide".
On Thursday he used an extraordinary meeting of the Organization of Islamic Cooperation (OIC) to call for an end to the "unspeakable cruelty" being unleashed against the Muslim minority.
His comments drew an angry response from Myanmar, which denies the allegations of abuse of the Rohingya, instead blaming "fake news" for spreading unfounded accusations.
Najib is "is using Myanmar for his own political interests, against the principles of ASEAN," deputy director of Myanmar's foreign ministry, Aye Aye Soe, told AFP, citing the Southeast Asian bloc.
"They criticise us without hesitation based on news reports from different places, including news from unreliable sources, without discussing the issue like a good neighbour. We are deeply sorry about this."
Analysts say Najib's embrace of the Rohingya is at least in part aimed at burnishing his image after allegations of massive graft linked to state fund 1MDB - a claim he denies.
His criticism of Myanmar marks a rare public spat between ASEAN members, which prides itself on non-interference.
The treatment of the Rohingya, a stateless group denied citizenship in Myanmar, has galvanised anger across the Muslim world.
Many among Myanmar's Buddhist majority call them Bengalis - shorthand for illegal immigrants from neighbouring Bangladesh - even though many have lived in Myanmar for generations.