Dhaka, Sep 6 (DPA) Thousands of opposition activists throwing rocks and burning tyres fought with riot police in this Bangladesh capital Wednesday, defying an overnight ban on rallies around key areas, witnesses said.

At least 70 people were injured in clashes, which turned central Dhaka streets into battlefields. The violence erupted as protesters tried to push back police barricades in the central Dhanmodi district, witnesses said.

The ban on rallies and street marches was imposed by the ruling coalition in Bangladesh ahead of a week-long campaign of protests planned by the opposition Awami League and its allies.

The opposition has called for reforms in a bid to ensure the credibility of the upcoming general election in January 2007 for a new 345-seat national parliament.

It is also demanding the sacking of the current Chief Election Commissioner M.A. Aziz, accusing him of being partisan to the governing coalition.

More than 5,000 additional police and other security forces were deployed to prevent a march to the central election office in Dhaka's northern Sher-e-Bangla Nagar district, official sources said.

Among the critically injured in the violence was Sabir Chowdhury, political adviser to opposition chief Sheikh Hasina.

The coalition headed by Prime Minister Khaleda Zia's Bangladesh Nationalist Party is expected to hand over power to a non-party caretaker government at the end of its tenure in October.

The caretaker government will hold the national polls within the next three months under the country's constitution.