A bag with an explosive charge was found in a Stockholm park on Sunday night during an annual cultural festival in which Iranian popstar Ebi was performing. 

Police in Sweden said Monday that the content of the bag was immediately “assessed as dangerous” and that the National Bomb Squad has opened an investigation into the attempted public destruction. The finding prompted police to cordon off the area while traffic was briefly re-directed.

The Swedish newspaper Aftonbladet said it contained a bomb and was found near the Cafe Opera, a famous nightclub. 

“It is only after the investigation at the national forensic center that we can say whether the dangerous object was functional," said Erik Åkerlund, local police manager. At the moment no one is in custody.

The five-day Stockholm Culture Festival wrapped up on Sunday with a concert by legendary pop singer Ebi, whose real name is Ebrahim Hamedi and is a known Iranian dissident. 

Tensions are relatively high between Iran and Sweden over a Swedish court’s sentencing of former Iranian jailor Hamid Nouri to life imprisonment over executions of political prisoners in 1988.

While human rights advocates such as UN High Commissioner for Human Rights Michelle Bachelet and Amnesty International have lauded the decision as a historic conviction and "an unequivocal, and long overdue, message to the Iranian authorities” for crimes against humanity, the Islamic Republic “strongly condemned” the court’s “politically-motivated and unacceptable” verdict. 

In June, the Swedish Ministry of Foreign Affairs advised its citizens against traveling to the Islamic Republic due to the security risks to foreigners.