Engineer Abdur Rahim Mia attended an organizational meeting of Kirtipasha Union BNP at the Union Parishad hall and offered flowers to BNP leaders.
Mia is identified as the Union Parishad chairman and a vice-president of the union Awami League.
BNP leaders including S M Ejaj Hasan and Khokon Mallik were present at the meeting.
Ejaj Hasan said Mia had not joined BNP and was not admitted to the party.
Hasan said BNP was not accepting new members under a central party directive.
Khokon Mallik said the meeting had been moved to the council hall because of adverse weather, and that Mia offered flowers and refreshments as a courtesy.
The incident drew criticism after images and video of Mia at the meeting circulated on social media.
Local BNP, Jatiyatabadi Swechchhasebak Dal and affiliated activists later locked the main gate of the Union Parishad office and protested.
The protesters declared Mia unwelcome and objected to holding the party meeting at the council building.
Swechchhasebak Dal leader Hafizur Rahman Murad alleged that people accused of obstructing and attacking the July uprising should not share a platform at party programmes.
An unnamed local BNP faction alleged that several lakh taka had changed hands in connection with the episode, but no supporting evidence was specified.
Mia said his family had longstanding ties to BNP, that he believed in Ziaur Rahman’s ideals, and that he was interested in associating with BNP politics in future.