Homemade bombs exploded in Bangladesh's capital and police fired tear gas at demonstrators as opposition parties enforced a general strike on Thursday, demanding that the government to restore an election-time caretaker administration.
Schools and businesses were closed in Dhaka and other major cities and towns during the eight-hour shutdown. Nationwide transportation was largely disrupted during the second opposition strike this week.
Witnesses and TV stations reported that police fought pitched battles with opposition activists in parts of Dhaka, but it was not immediately clear if anyone was injured in the violence.
Several vehicles whose drivers tried to defy the strike were either torched or smashed in Dhaka on Thursday, police said.
Bangla Vision and Massranga television stations said dozens were 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. A key coalition partner is also pressing for freedom of its leaders facing charges of crimes against humanity involving 1971 independence war against Pakistan.
The protest is led by main opposition Bangladesh Nationalist Party. Former Prime Minister Khaleda Zia is the head of the party.
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 criticized the trial, calling it politically motivated.
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 — at the time the eastern wing of Pakistan — became independent, aided by India, after a nine-month war against Pakistan.
Zia's party demanded release of a senior leader who was arrested on charges of instigating violence earlier this week.
The government of Prime Minister Sheikh Hasina 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.
Hasina's government said the main opposition must return to parliament and place any alternative to the system for next elections. Lawmakers from Zia's party have been boycotting parliamentary proceedings for months amid street protests.
Hasina's Awami League party and Zia's Bangladesh Nationalist Party are the main contenders for power.
The opposition enforced a nationwide road blockade on Sunday and a nationwide general strike on Tuesday. The protests turned violent.
The South Asian country, a parliamentary democracy, has a history of political violence.
The United States has urged the government and the opposition to sit across the table to remove differences over the election row.
The country's top business leaders on Wednesday urged the both sides to shun the politics of confrontation and resolve disputes through discussion.
The government has blamed the opposition for the recent violence, saying the protests are aimed at protecting the 1971 suspects. The administration has vowed not to go back to the caretaker government system.