Witnesses say Myanmar authorities detained dozens of members of the opposition party as they returned home from ceremonies to mark the death of the father of jailed opposition leader Aung San Suu Kyi.
Witnesses, who spoke on condition of anonymity fearing reprisals, say at least 50 National League for Democracy members were arrested on Sunday.
They said some had been attending a ceremony at party headquarters in Yangon to mark the death 62 years ago of Gen Aung San. Others had been at an official commemoration at a monument dedicated to the independence hero.
It was not immediately clear why police detained them.
Aung San was assassinated July 19, 1947, shortly after Britain granted independence to the Southeast Asian colony.