Myanmar President Thein Sein has declared a state of emergency in a central town where at least 20 people have been killed in violence between Buddhists and Muslims.

The president made the announcement in a statement broadcast on state television on Friday.

The government's struggle to contain the unrest in the town of Meikhtila is proving another major challenge for Thein Sein's reformist administration as it attempts to chart a path to democracy after nearly half a century of military rule that once crushed all dissent.