The man, a Swedish citizen, was arrested on Tuesday morning in the Gothenburg area, Göteborgs Posten reports. A warrant for his arrest had been issued some time ago, according to police.

He was originally arrested on suspicion of ‘crimes against national security’, but police later said he was now being held pn suspicion of ‘conspiracy to commit acts of terror’.

Police must either charge or release the man by Friday.

Prosecutors were on Tuesday giving little information about the man or the nature of the accusations against him. Agneta Hilding Qvarnström, at the national prosecutors’ office for security cases in Stockholm, told Göteborgs Posten:

“The identity is classified, the circumstances are classified, everything is classified.”

The Security Service warned recently that Al-Shabaab, an al-Qaeda-linked extremist group in Somalia, had recruited more than 20 young people from the Gothenburg area to fight in the war-torn country. It is not known whether the latest arrest is linked directly to the warning.