“One person has been arrested today, supected of conspiracy to commit acts of terror,” said Agnetha Hilding Qvarnström at the International Prosecutor’s Office in Stockholm.

A warrant for the man’s arrest was issued some time ago. He is wanted on ‘probable cause’, the highest grade of suspicion in the Swedish system.

The man was born in 1984 and is of Somalian origin, according to Expressen. He was arrested by heavily armed police.

Hilding Qvarnström confirms that the case is linked to the charges laid against a man in Gothenburg suspected of the same offence.

“There are links with the investigation in Gothenburg,” she said.

Hilding Qvarnström has until Friday to decide whether to charge the man or to release him. Asked whether more arrests were expected, she said:

“You can never know, but now we are continuing our work. The investigation is underway.”

The prosecutor would not confirm the man’s age or that he was of Somalian origin. Nor would she confirm the link to al-Shabaab. She said the arrest was undramatic:

“As far as I know it was orderly.”

The Swedish Security Service (Säpo) has stated that it has a duty to prevent people travelling from Sweden to take part in acts of violence in war zones, including Somalia.

At least 20 people are known to have travelled from Sweden to Somalia to be trained or participate in acts of violence, according to the Security Service. The service says that it has information relating to four identified Swedish citizens who have been killed in Somalia during the conflict.