Tens of thousands of opposition supporters in Bangladesh have taken part in a mass rally in Dhaka.
The protesters called for the government to step down and hold new elections under a neutral caretaker administration.
Riot police and the security forces surrounded the rally, but police said no serious clashes were reported.
Correspondents say it was the biggest such protest since the opposition were defeated in elections in 2008.
Police say that about 100,000 people took part in the protest - schools and businesses in the area were closed.
The Bangladesh Nationalist Party (BNP) said that hundreds of its members were arrested before the protest began.
BNP leader Khaleda Zia said the opposition alliance would stage a nationwide general strike on 29 March and increase their protests if the caretaker system was not restored by June.
"We will announce a series of protests across the country if the government fails to accept our demand,'' she told the cheering crowd.
Under the system supported by the BNP, a caretaker administration would govern the country during the election campaign to ensure the vote is conducted in an "impartial manner".
The BNP believes elections overseen by the incumbent government would neither free nor fair and has said it will not take part if the caretaker government system is not restored.
But the governing Awami League has rejected the idea. It says that the vote will be free and fair under its supervision. The election is due to be held in 2014.
Some warn that the political turmoil could threaten the country's already weak economy and drive away investors.