Bangladesh has come to a virtual standstill as a 36-hour general strike called by the opposition Awami League-led alliance got under way.
The strike has closed shops, offices and schools and hit transport in Dhaka and more than 60 cities and towns.
The Awami League and its 13 allies have called the strike to protest against alleged police brutality against their supporters on Sunday.
Some 200 people were injured in clashes during opposition protests in Dhaka.
The opposition is pressing the government to reform the electoral system ahead of polls due in January.
An unelected interim administration is due to supervise the elections. The opposition says it will be full of government supporters.
Thousands of security forces have been deployed in the capital, Dhaka, for the strike.
Police used tear gas and batons against hundreds of opposition activists who were trying to march into the capital's Mahakali area, the Associated Press news agency reports.
'Politically motivated violence'
Sunday's action was part of a campaign against the government, which the Awami League and its allies say is incompetent and corrupt.
The strike is due to last three days
The ruling Bangladesh National Party has condemned the "violence and vandalism" by the opposition and urged citizens to resist the strike.
Analysts say Bangladesh is headed for more violence in the run-up to January's elections.
British High Commissioner Anwar Chowdhury has expressed "grave concern about the level of politically motivated violence which risks tarnishing Bangladesh's reputation as a democracy".
Opposition groups want the government to agree electoral reform proposals to ensure the next general election is free and fair.
They are also demanding the resignation of chief election commissioner MA Aziz, whom they accuse of not being neutral. Mr Aziz denies the allegations.
Prime Minister Khaleda Zia has promised to stay in office until October.
Under the constitution, she must hand power to a caretaker administration to oversee the election.
Her government has blamed the opposition for the deadlock in talks on electoral reform.