He made the call in an unofficial note to the chief election commissioner and the returning officers of Dhaka North and South on Monday.
It came amid the prevailing confusion over the role of MPs and ministers in election-related activities and campaigns of candidates contesting in the polls on Jan 30.
In the note, Mahbub observed that the existing electoral code of conduct does not allow lawmakers and ministers to be a part of any campaign-related committee regardless of whether it conducts its activities at home or in public.
The election commissioner believes it is 'imperative' to publish a circular with clear instructions on the issue in order to quell any confusion. Otherwise, the Dhaka city corporation elections will be open to question, he warned.
"There will be a crisis of confidence in the EC if it fails to ensure the strict observance of the election code of conduct in the Dhaka city corporation polls."
The note was also sent to the three other election commissioners.