“The current case is one of several that the Swedish Security Service has been working on… in connection with the high-profile Koran burning,” said Susanna Trehörning, deputy head of the security service’s counterterrorism unit, adding that suspects were linked to international “Islamic extremism”.

The five men were seized in raids in Eskilstuna, Linköping and Strängnäs, in central Sweden.

They are being held on so-called “reasonable suspicion”, which is the lower degree of suspicion in Swedish law.

The security service said they did not believe an attack had been imminent. In a statement they added they “often have to intervene early to avert a threat. We cannot wait for a crime to be committed before we act”.

The prosecutor has to decide by April 7th whether or not to request that the court remand the men in custody.

Far-right activist Rasmus Paludan, pictured above, in January burned a copy of the Quran outside the Turkish embassy, sparking fury in Turkey and several Muslim countries. The security police said the incident made Sweden a higher priority target for terror attacks.