Is it 21 or IS? Confused Swedish cops raid house

In a bizarre mix-up, Swedish police raided an apartment after a couple hung 21-shaped balloons to celebrate a birthday but it was mistaken for 'IS' in a reverse image from outside and considered as the Islamic State propaganda.

Sarah Ericsson hung up the balloons in the shape of the number '21' for her birthday which resulted in her home in Karlskrona, Sweden, being visited by Swedish police who  thought it stood for 'IS' and had been put up by supporters of the Islamic State extremist group.

"It was a little strange," the 21-year-old told The Local from the library at the Blekinge Institute of Technology in southern Sweden, where she is taking a course in Spatial Planning.

The student was already in class on Monday when her boyfriend Fabian Akesson, who was staying at her house, received a visit from police.

A passerby had called them after looking through the window at the two balloons pushed together to make the number '21' and confusing their reverse image with the letters 'IS', which the extremist group also known as the Islamic State often uses as part of its propaganda.

"We understand why someone would report it if they thought it looked like IS-propaganda, although everyone else just thought it looked like the number '12' from outside," Ericsson said.

Her boyfriend Akesson explained that he was looking out of a window brushing his teeth when he noticed several police cars outside the house and then heard a knock on the door.

When he went to open it, he was greeted by three police officers, who quickly realised that they had made a mistake. "I laughed about it and they showed me a photo that they had taken where from their perspective, it did almost look like the letters IS," he told Swedish newspaper Kvallsposten.

But despite police accepting the error, Akesson said he was still asked to remove the balloons from the window. "They asked me to take down the balloons to avoid further misunderstanding. We laughed some more about it all and they wished me a nice day, and wished my girlfriend a belated Happy Birthday," he said.

"Extremism should always be taken seriously, and we did take the balloons down immediately," Ericsson said. "I'm so surprised at all the attention. I will never forget my 21st birthday!" she added.