The additional police and barricade around the Bangladesh Nationalist Party (BNP) chief's upmarket Gulshan district office was removed around 3 am local time.
"They (police) first removed their vans at around 2.30 am and afterwards they left the scene along with water cannons," a BNP official told reporters adding that few policemen were left behind for routine duty.
The withdrawal of security coincided with the 79th birth anniversary of Zia's husband and BNP's founder Ziaur Rahman.
State minister for home Asaduzzaman Khan Kamal last night said that the 69-year old Zia, would not be barred from visiting Rahman's grave and she could move anywhere after offering wreaths there.
Zia, a former two-time premier, was "confined" to her office since January 3, ahead of the BNP-led 20-party alliance's much talked-about rally marking one year of the disputed January 5 elections won by her arch rival Prime Minister Sheikh Hasina.
The siege around her office triggered renewed political unrest across Bangladesh that has left 28 people dead.
During the siege at the two-story building, the opposition leader called a nationwide transport blockade, with the opposition party activists firebombing buses, cars and other vehicles, leading to police retaliate by firing bullets and
tear gas.
Zia wants Hasina to call fresh elections after last year's controversial poll boycotted by opposition parties.
The opposition boycotted the polls over their demand to hold the polls under a neutral caretaker government.
Two police vans and a water cannon placed on the two ends of her residence left the area early on Monday. Most of the police personnel deployed around her office also left the area by 3:30am.

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