Warning the government not to create any obstacles for the movement she dubbed the "March for Democracy", Zia said the upcoming general election "could be the last nail in the coffin of democracy".
The BNP is boycotting the polls and political violence during nationwide strikes and blockades enforced by an opposition alliance have left over 100 people dead and crippled the economy since November.
"We have named it the 'March for democracy'. I urge all able bodied countrymen cutting across their affiliation, religion and class to join the rally on December 29," former premier Zia said.
Besides the BNP-led 18 party opposition alliance, a key ally of premier Sheikh Hasina's Awami League party has also boycotted the polls. Hasina, however, insists the vote will go ahead as planned.
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The BNP has refused to field candidates for the election, saying the vote under Hasina will be rigged - an accusation the premier strongly rejects.
The Bangladesh Nationalist Party (BNP)and its allies have been staging protests since late October to force Hasina to step down so that a non-party caretaker government can be installed to oversee the election.
However, she has said she would consider dissolving the parliament formed after the polls and holding another election if the BNP shuns violence and severs ties with the fundamentalist Jamaat-e-Islami.
UN chief Ban Ki-moon's envoy Oscar Fernandez-Taranco came to Dhaka in early December and persuaded the Awami League and BNP to hold a dialogue to find a political solution. But they failed to reach an agreement even after three rounds of talks.
Zia today said there were still scope for negotiations. "Still there is time and we are ready for talks," she said.