Explosions and clashes have marked an opposition protest in the Bangladeshi capital Dhaka, where demonstrators are calling for an election-time caretaker administration to be restored.
Schools and businesses were closed in Dhaka and other major cities on Thursday, during an eight-hour general strike.
Nationwide transportation was largely disrupted during the second opposition strike this week.
Witnesses and local media reported that riot police had fought pitched battles with opposition activists in parts of Dhaka. It was not immediately clear if there were any injuries in the violence.
Those enforcing the strike torched or smashed several vehicles belonging to those who were not observing the shutdown, police said.
Local media also reported that dozens had been detained in major cities.
A coalition of 18 opposition parties was enforcing the strike to demand that the caretaker government be restored before the next national elections due in 2014.
The government of Sheikh Hasina, the prime minister, last year scrapped the 15-year-old caretaker government system during elections following a Supreme Court ruling that the constitution allows only popularly elected governments.
Opposition parties fear the election will be rigged if the current party remains in power.
Prisoners' release demanded
The protest is led by the main opposition Bangladesh Nationalist Party of former Prime Minister Khaleda Zia.
Jamaat-e-Islami, the country's largest Islamic party and the main partner of Zia's party, has been demanding the release of nine of its leaders facing charges of crimes against humanity. Two other leaders from Zia's party face similar charges and are now jailed.
Zia has criticised the trial, calling it politically motivated. Her party has also demanded the release of a senior leader who was arrested on charges of instigating violence earlier this week.
Jamaat-e-Islami leaders are accused of abetting the Pakistani army in killing and raping during the war. The party says the charges are aimed at weakening it.
In 1971, Bangladesh - then the eastern wing of Pakistan - became independent, aided by India, after a nine-month war against Pakistan.