The initiative was launched after a woman was found dead on a running track in Upplands Väsby last week – to show defiance in the face of fear after police branded her death suspicious and advised residents in the area to be careful when out running on their own.

“We're reclaiming the right to be able to run without being afraid,” Ulrika Säfström Sunnerfelt, one of the organizers behind the campaign, told Swedish newswire TT.

Around 20,000 people had joined the Facebook event saying they would go for a run on Sunday. Säfström Sunnerfelt herself ran around the Rocklunda trail in Västerås, some 80 kilometres from Upplands Väsby, together with around 70 people from all ages.

“It feels tragic that this is even needed. But I am incredibly happy that so many have chosen to be here to show that everyone has the right to move around freely in society,” she said.

And in Upplands Väsby around a hundred runners gathered to take part on Sunday in memory of the suspected murder victim, who lived in the town in central Sweden.

“Everyone I meet on the trail always ask me how I can be running alone, but I refuse to let myself be affected. It feels like we're honouring her by doing this together,” orienteering enthusiast Amanda Jonasson, 25, told the Aftonbladet tabloid.

The campaign, called 'Run With Love' ('Spring med kärlek') was organized after a 21-year-old woman was found dead at 2.05am on Thursday morning in the Runby area of the Stockholm suburb of Upplands Väsby by dog handlers.

Her family had reported her missing at 9.30pm on Wednesday when she did not come home after a short jog.

Meanwhile, police are still investigating the suspected murder. No arrests had yet been made as of Monday morning.

“We're continuing to work unabated, checking information received and awaiting answers to the forensic investigation,” said Stockholm police spokeswoman Eva Nilsson.