"As for the happenings in the middle of the night, this is not what you expect from a working democracy," Aung San Suu Kyi said.
A tense situation has developed at the headquarters of Myanmar's ruling Union Solidarity and Development Party (USDP), where those attending a party meeting are not being allowed to leave by security forces.
The United Nations is stepping up its emergency aid to Myanmar, where massive floods have killed at least 96 people in the country's Irrawaddy delta region.
The United States says it will announce an aid package to help floods victims in Myanmar, as international aid efforts have accelerated after the disaster affected tens of thousands across the country.
Authorities in Myanmar say 46 people are now dead after several days of flash flooding and landslides.
The civilian-led government of Myanmar has appealed for urgent international assistance to help aid victims of the country's recent flooding.
Myanmar opposition leader Aung San Suu Kyi visited one of the country's many flood-hit areas, raising her profile amid a national disaster that could have consequences in this November's general election.
Myanmar authorities say 21 people died in July, and that between 67,000 and 110,000 people were "severely affected" by the floods, according to an update from the U.N. Office for the Coordination of Humanitarian Affairs (OCHA).
Myanmar, also known as Burma, has freed nearly 7,000 prisoners, including 155 Chinese nationals who last week were sentenced to life in prison for illegal logging.
China on Thursday criticized long prison sentences in Myanmar given to more than 150 Chinese nationals convicted of illegal logging. VOA Correspondent Steve Herman reports from our Southeast Asia bureau in Bangkok.
Myanmar has sentenced 153 Chinese nationals to life in prison for illegal logging in northern Kachin State.
Myanmar's main opposition National League for Democracy is reaching out to other activists to bolster its position ahead of elections later this year.