At least six people have been killed and more than 100 injured across Bangladesh and more than 100,000 opposition activists rallied in the capital, Dhaka, on Friday to demand that Prime Minister Sheikh Hasina quit and order polls under a caretaker government.
Police said the protesters died after officers and border guards opened fire in three towns as the supporters of the Bangladesh Nationalist Party (BNP) and its Islamist allies protested across the country, AFP news agency reported.
Two protesters were killed and several others were injured by bullets in the southern resort district of Cox's Bazaar when border guards opened fire at several thousand supporters of the BNP.
"The border guards opened fire after the BNP activists defied a ban on rallies and attacked the forces," Cox's Bazaar district deputy police chief Babul Akter told AFP.
Several television channels reported that three people died in the central district of Chandpur when police and ruling Awami League supporters clashed with opposition supporters.
At least 30 people were injured in the clash in the area, which is 64km east of the capital.
A demonstrator died in the northern town of Jaldhaka after the elite Rapid Action Battalion opened fire at about 10,000 rampaging supporters of the Jamaat-e-Islami party, a key ally of the BNP, area police head Mohammad Moniruzzman told AFP.
The violence also spread to the eastern district of Comilla, where at least 20 people were injured.
Similar clashes were also reported in Bangladesh's second-largest city, Chittagong, which is in the southeast, and in many other towns across the country.
In Dhaka, opposition supporters allegedly set fire to a car and a bus, but no injuries were reported.
At least 10 homemade bombs were exploded at a premier public university area in Dhaka.
Ruhul Kabir Rizvy Ahmed, a spokesman for the opposition Bangladesh Nationalist Party, said at least 400 opposition supporters were arrested across the country.
The clashes occurred as the BNP and its Islamist allies called nationwide mass protests to force Hasina to resign ahead of the January 2014 elections and set up a technocrat-led caretaker government to oversee the polls.
BNP leader Khaleda Zia addressed a rally of over 100,000 supporters at a national memorial in central Dhaka, renewing her threat to boycott the polls and setting Hasina a new weekend deadline to hold a dialogue on her demand for a caretaker government.
"There will be no election under Hasina. We won't allow any one-party election. The election must include all parties and be conducted by a neutral caretaker government," Zia told the crowd, announcing a nationwide strike for Sunday to Tuesday to press her demands.
Bangladeshi politics has long been dominated by a feud between the two dynastic leaders who distrust each other.
Local Dhaka police chief Sirajul Islam put the number of the crowd at the rally at "over 100,000". Witnesses and BNP officials said the figure was double.
Tensions have been rising in Bangladesh since Hasina's ruling Awami League (AL) party rejected an October 24 deadline set by the BNP for accepting its demands.
Zia, who has twice served as premier, branded the government "illegal" as of Friday, citing a legal provision that requires a neutral caretaker government to be set up three months before elections slated for January 2014.
But the ruling AL abolished the provision in 2011, handing the job of overseeing polls to a reformed Election Commission.
The government has deployed thousands of police and paramilitary border guards in Dhaka, in the port city of Chittagong where the ruling party called a rival rally that was peaceful, and other potential flashpoints.
"We've sent BGB (Border Guard Bangladesh) troops to 20 major cities and towns," BGB director colonel Hafiz Ahsan told AFP.
Police said they fired rubber bullets in half a dozen other towns, leaving scores injured after the supporters of the AL party and the BNP clashed.
While the nation has a long history of political violence, this year has been the deadliest since Bangladesh gained independence in 1971.
At least 150 people have been killed since January after a controversial court began handing down death sentences to Islamist leaders allied to ex-premier Zia.