Witnesses said more policemen were deployed around the office of the Bangladesh Nationalist Party chief in upmarket Gulshan area in the capital.
They said the employees of the office used the picket gate of the compound to bring food for Zia and other party leaders, mostly women, who are with her inside the building.
State Minister for Home Asaduzzaman Khan Kamal described the police action as part of initiatives to intensify the "ex-premier's own security" and said the government would provide the security "as long as she needed it".
Violence coinciding with the first anniversary of the January 5, 2014 general elections yesterday killed four people in different parts of Bangladesh in clashes between the activists of BNP and ruling Awami League supporters.
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A paramilitary soldier was critically burnt today when pro-blockade activists torched his van at Kadamtali area.
The anti-government activists also set on fire a unit office of ruling Awami League at Demra on the outskirts of the capital where the traffic was thin with private vehicles staying off the street fearing outbreak of violence.
Prime Minister Sheikh Hasina last night asked Zia to shun the "path of anarchy" and prepare for future elections during a nationwide televised address marking the anniversary of the January 5 polls, which was boycotted by BNP.
"The path you (Zia) are walking will not usher in peace. (Rather) You will lose further the people's confidence as they want security, peace and development," the premier said.
Hasina's address came hours after Zia called for the non-stop blockade from today as part of her campaign demanding fresh elections under a non-party caretaker government.