DHAKA  - One person was killed and at least 30 others injured Monday when police clashed with thousands of opposition protesters in Bangladesh's northwestern city of Rajshahi, police said.It comes a day after four activists from the main opposition Bangladesh Nationalist Party (BNP) were killed when police fired on demonstrators in the southeast of the country.Tensions also ran high in the capital after the ruling Awami League party and the BNP called rival rallies in central Dhaka.BNP and its allies have been staging large protests around the country in an effort to force the government to call early elections.In the latest deadly disturbance, police fired rubber bullets and tear gas at more than 5,000 supporters of the BNP and its allies after their rally turned violent, Rajshahi police commissioner M. Obaidullah told AFP. "We can confirm the death of one person," he said, adding five police officers and 25 other people were injured during the clashes.Police said the number of casualties could rise as the violence spread to at least four key places in the city of about half a million people.In Dhaka, two-time former prime minister Khaleda Zia led a mass BNP procession, while the Awami League staged a rally a short distance away.Authorities had banned the processions in the capital planned for the weekend over fears the two sides could clash.Opposition anger was fuelled when the government, led by Prime Minister Sheikh Hasina, last year scrapped a caretaker system for overseeing elections.The next national election is due to be held by early 2014.