Southeast Asian and Western countries have urged all sides in Myanmar to refrain from violence and allow in humanitarian aid, after the National Unity Government (NUG) declared a nationwide uprising against the junta, Reuters reported.

A military spokesman dismissed the call as a futile effort to gain world attention.

Regardless, security forces were out in strength in Myanmar's biggest city, Yangon, on Wednesday, a day after protests and a flare-up in fighting between the army and ethnic minority insurgents.

Britain's Ambassador to Myanmar Pete Vowles on Facebook condemned the coup and what he called brutality by the junta and urged "all sides to engage in dialogue".