Southeast Asian foreign ministers mediating on the crisis in Myanmar called on Monday for its military rulers to free prisoners and start an agreed political dialogue, expressing disappointment at "very slow" progress so far.

The United Nations, Western countries and China back the effort by the 10-member Association of Southeast Asian Nations (Asean) to find a way out of the crisis in Myanmar, a country paralysed by turmoil since a Feb 1 coup that ended a decade of tentative democracy.