BNP on Tuesday turned down the election results of Barishal and Rajshahi city corporations and demanded re-election to the two cities.
The party will stage demonstrations in all the towns and metropolitan cities on Thursday to press home its demand.
BNP secretary general Mirza Fakhrul Islam Alamgir came up with the announcement at a press conference at the party's Nayapaltan central office.
"Out of three cities, we turned down the election results of Barishal and Rajshahi. We also demand cancellation of the results and re-election to the two cities," he said.
About Sylhet city polls, Fakhrul said their party mayoral candidate could have won with a margin of over one lakh votes had the election been held in a free, fair and credible manner, UNB reports.
The elections to Rajshahi, Barishal and Sylhet city corporations were held on Monday.
Awami League mayoral candidates were unofficially declared elected in Rajshahi and Barishal city polls on Monday, while the announcement of the results was postponed in Sylhet as the number of votes in two centres where voting was suspended is higher than the difference between the two leading candidates' tallies.