Officials and witnesses in Burma say an explosion at a post office has wounded a postal worker.
The blast in Rangoon today is believed to have been caused by a letter bomb. No other injuries were reported.
In the past, Burma's military-run government has blamed small bomb attacks on exile groups that oppose military rule.
Some dissidents say the blasts are carried out by government-linked groups to justify tighter security.
Burma has been under military rule since 1962.
The government was strongly criticized this week at the Association of Southeast Asian Nations summit in the Philippines, where regional leaders called on Burma to enact democratic reforms.