A reporter from the Swedish newspaper Gefle Dagblad was threatened by an imam over the journalist's investigation into a Muslim school thought to be linked to a local mosque in the city of Gavle, Expressen reports.

The incident took place during a recent meeting between the reporter and the school's manager, who admitted a link between the school and the Gavle mosque.

The meeting was also attended by an imam from the mosque who had rejected Gefle Dagblad's requests for an interview over the past four years, which had prompted the reporter to seize the opportunity.

The situation dramatically escalated after a "third man" started to film the interview; following the encounter, the imam became furious and ordered the reporter to delete the video.

Commenting on the incident, Gefle Dagblad's editor-in-chief Anders Ingvarsson said that "when a reporter, under threats, insults and waving fists, is forced to erase images, one has passed a border where one threatens our democracy and freedom of the press".

"The direct threat was to the reporter, but through this, one affects journalism for all our readers and our ambition to portray reality," Ingvarsson pointed out.

The incident comes amid reports that Islamic radicalisation-related problems have been on the rise in Sweden for the past few years.

According to a survey by the Swedish Defence College, within less than a decade, Sweden's extreme Islamist community has grown from 200 members to 2,000, with Salafism playing a vital role in the spread of violent Islamism in a number of Swedish cities, including Gothenburg. 

Peder Hyllengren of the Swedish Defence College, for his part, claimed that Sweden had already turned into an international hub for extremists.

The exact number of Muslims in Sweden is a matter for debate due to the absence of religion-based statistics. A 2017 report by Pew Research Center estimated that 8.1 percent of Sweden's population of 10 million was Muslim, the highest percentage in Scandinavia and one of the highest in the EU.