Police in Bangladesh are on alert after supporters of a hardline Islamic preacher responded to his call to replace World Cup supporters’ flags with Islamic banners across the country.

The campaign followed a speech by Muslim cleric Mufti Harun Izhar, who urged supporters to take down the flags of football powerhouses Argentina and Brazil and instead display white flags bearing the Kalima, the Islamic declaration of faith.

According to authorities, the flags have been raised in more than a dozen districts, prompting increased security monitoring. Police spokesperson Shahadat Hossain said officers would intervene if the displays threatened public order.

“We are on alert,” Hossain said, adding that action would be taken if the campaign created security concerns.

Videos circulating online also showed supporters staging motorcycle rallies while carrying the white flags and playing religious songs.

Speaking to AFP, Izhar said people should exercise restraint in displaying support for foreign football teams. He also rejected suggestions that the white flags were linked to Afghanistan’s Taliban authorities or the extremist group ISIS.

“Secularists have certain attitudes towards these flags and readily label them Taliban or ISIS flags. That is not correct,” he said.

The development has drawn attention from the government, with Prime Minister’s adviser Zahed Ur Rahman warning that the campaign could damage Bangladesh’s international image.

Meanwhile, some football fans have defended their support for the sport. Brazil supporter Mohammad Moniruzzaman Chisty said football provides people with a welcome escape from daily challenges, describing it as “the ultimate form of entertainment.”