Dozens of police searched BNP chief Zia's office in the upscale Gulshan neighbourhood for two hours early this morning, but later said they did not find "any materials".
Police said they had a search warrant, but Bangladesh Nationalist Party alleged that law enforcers acted on an unknown general diary only to harass Zia, 71, who is facing about three dozen cases of alleged graft, treason and violence, local media reported.
Hundreds of supporters of Zia's BNP staged a protest outside the two-storey office building.
Earlier in the day, Gulshan Police Station OC Abu Bakar Siddique had said: "We have a court order to check if there is anything in the office that could compromise national security."
BNP and its front organisations today announced that they will hold countrywide demonstrations tomorrow to protest against the police raid.