Violence erupted across Bangladesh on Monday as the nation marked the anniversary of controversial elections last year. Four people were killed and more than 400 were injured in politically motivated clashes.
Two activists from the main opposition party's student wing were killed when gunfire broke out between rival political camps in Natore, a district 100 miles northwest of Dhaka, the capital, party officials said.
Two more opposition activists were killed when police opened fire on rallies in two other northern districts, according to party members.
Fears of violence spread as opposition leader Khaleda Zia vowed to challenge a police ban on protests in Dhaka, calling on supporters to besiege roads, highways, railways and naval routes. Police stopped most road and ferry access to Dhaka, effectively cutting off the capital from the rest of the impoverished South Asian nation.
"This government has denied our right to hold a rally. The siege program will continue," Zia, the former prime minister, told reporters gathered inside her office in Dhaka.
Zia has been confined to her office since Saturday night as police sought to quell tensions ahead of Monday's anniversary of last January's parliamentary elections, which were marred by deadly violence. Zia's Bangladesh Nationalist Party, which boycotted the polls along with an alliance of opposition parties because of concerns over fraud, has demanded fresh elections and a reshuffled election commission.
In a televised address Monday night, Prime Minister Sheikh Hasina again refused calls to step down and accused opposition supporters of destabilizing Bangladesh.
Police early Monday blocked Zia's office, in Dhaka's upscale Gulshan neighborhood, with a dozen sand-laden trucks and deployed extra police to keep her from joining a planned anti-government rally. When supporters tried to force open the gate from inside, police used pepper spray to turn them back.
Police also reportedly arrested thousands of opposition supporters who took to the streets in Chittagong, the country's main port, and other cities. Clashes broke out on the grounds of the Supreme Court premises and National Press Club in Dhaka, and anti-government protesters set fire to vehicles in the streets.
Special correspondent Kader reported from Bangladesh and staff writer Bengali from Mumbai, India.