Myanmar has been in chaos since the coup, with conflict spreading across the Southeast Asian country after the army crushed mostly peaceful protests in cities.

Asean should state explicitly that executing dissenters is the ultimate act of violence and that it expects Myanmar to desist from such behaviour immediately.

It says the men were given due process and insists those executed were not democracy activists, but killers deserving of their punishment.

Saifuddin Abdullah slams the move to execute four pro-democracy activists whom the junta accused of aiding 'terror acts' by a civilian resistance movement.

US State Department spokesperson Ned Price has called on countries to ban sales of military equipment to Myanmar and refrain from any action that would lend the junta any international credibility.

Sentenced to death in January in a closed-door trial, the four men had been accused of helping militias to fight the army that seized power in a coup last year and unleashed a bloody crackdown on its opponents.

The plans are described as safe city projects aimed at maintaining security and, in some cases, preserving civil peace, say the people who are or have been involved in the projects.

Suu Kyi has been kept virtually incommunicado by the military and was recently transferred from house arrest to solitary confinement while she faces multiple trials that could see her sentenced to more than 150 years in jail.

The junta has sentenced dozens of anti-coup activists to death as part of its crackdown on dissent after seizing power last year, but Myanmar has not carried out an execution for decades.

The northern Sagaing region has seen fierce fighting and bloody reprisals, with the junta calling in airstrikes and reports widespread of soldiers burning villages.

The investigation will add to global pressure on the military to halt its crackdown on opponents and the use of air strikes and shelling in civilian areas.

Mass protests against last year's coup have been met with a brutal military crackdown, and violence has flared as civilians form 'people's defence forces' to oppose the junta.