Säpo would not go into detail concerning the information it received or when it acquired it or from where it came. The agency did say that "the nature of this particular information is such that it cannot be dismissed".
The US embassy in Stockholm, however, wrote on its website that "Swedish Police are actively investigating a potential terror threat against Sweden".
The US embassy encouraged its citizens to be vigilant, especially in crowded places, on public transportation and at special events.
Security Message for U.S. Citizens: Police Investigation of Possible Threat in Sweden: https://t.co/nO5dKRvmZs— US Embassy in Sweden (@usembassysweden) April 26, 2016
The embassy had last issued a more general alert for citizens traveling "to and throughout Europe" on March 22 after the terrorist attacks in Brussels. The alert message said it is in effect until June 20.
Sweden’s terrorist threat level remained unchanged and Säpo advised the public to follow any instructions issued by the police.
In the meantime, Säpo said a special response team had been established to collect, process and analyze information. The team also takes decisions based on the information it receives and allocates staff and resources, Säpo said.