A mass rally is being staged in the Bangladeshi capital as an alliance of political parties keeps up pressure for national elections to be postponed.
Dhaka has seen violent protests in recent days
The Awami League party and its allies are demanding electoral reforms before the 22 January vote is held.
Their supporters and police have clashed violently during demonstrations over the past three days.
The latest protests come as thousands of troops are being deployed across the country to prepare for the poll.
An Interior Ministry statement said the army had powers to make arrests with warrants to ensure security for the election.
Charges of rigging
The BBC's John Sudworth in Dhaka says thousands of grand alliance supporters are expected to take part in Wednesday's rally close to the presidential palace in the centre of the city.
They will listen to their political leaders outline a new programme of action for the next few weeks aimed at disrupting the national poll.
Alliance leaders say the outgoing governing party, the Bangladesh Nationalist Party (BNP), is trying to rig the vote - allegations the BNP and the authorities reject.
The recent unrest has left Bangladesh facing a variety of unpalatable scenarios - certainly a discredited incomplete election or even a state of emergency, our correspondent says.
The president and chief adviser to the caretaker government, Iajuddin Ahmed, is insisting the elections must take place as planned in accordance with the timetable laid down by the constitution.