The junta -- which seized power in a 2021 coup sparking a many-sided civil war -- said it would cease attacking its myriad armed opponents following the magnitude-7.7 quake which has killed more than 3,700.

Conflict monitors and residents in combat zones say fighting continued on both sides during the 20-day truce, declared to spur aid delivery in Myanmar's central belt and which was due to expire at midnight (1730 GMT).

The ceasefire was extended to April 30 "aiming to continue the rebuilding and rehabilitation process with momentum", the junta information team said in a statement.

But the military said it would not hesitate to retaliate if other armed groups launched attacks -- as it said when it announced the ceasefire.

The March 28 earthquake has left more than 60,000 people living in tent encampments and pushed two million people into "critical need of assistance and protection", according to the UN.

Despite continued fighting, humanitarian groups and regional powers have called for the pause on hostilities to be prolonged as aid efforts continue into their fourth week.

On Thursday, junta chief Min Aung Hlaing flew to Bangkok to meet Malaysian Prime Minister Anwar Ibrahim for rare backroom talks with the chair of the 10-country ASEAN bloc.

Anwar, whose country currently holds the rotating chairmanship of the Association of Southeast Asian Nations (ASEAN), said he had also spoken to Myanmar's opposition "National Unity Government" which promised a similar truce after the tremor.

Both sides agreed "they would do whatever is necessary to avoid any extension of the fighting", Anwar told reporters after the meeting.