The man arrested over last week’s firework bomb attack on the D66 party office in The Hague acted with “terrorist intent”, the public prosecution service (OM) has said. A judge has subsequently extended his pre-trial detention by two weeks.

“An explosion targeting a political party’s office instils fear in part of the population,” prosecutors said. The suspect has not yet given a statement and the investigation into his motive is still under way.

Under Dutch law, prosecutors can attach terrorist intent to an offence when an act is aimed at instilling fear in the public, political coercion, or disrupting the country’s core social and constitutional structures.

No accusations as to the suspect’s ideological orientation or wider aims in the attack have been made public. Prosecutors have not released his name, but have disclosed that he is 37 and has no fixed address.

What happened

A firework bomb was thrown through the letterbox of D66’s national office on the Lange Houtstraat in The Hague shortly after 9pm on Thursday 7 May. About 30 members of the party’s youth wing, the Jonge Democraten, were inside for a meeting.

No one was hurt, but the blast tore the letterbox out of the door and shattered the glass above the entrance. Prime minister Rob Jetten, who also leads D66, called the attack “a cowardly act of intimidation” and the bombing drew condemnation from across the political spectrum. The office has since reopened.

It is the second attack on the same building in eight months. In September last year, rioters from an anti-immigration demonstration smashed the windows of the D66 office and pushed a burning container towards the building. Some of those involved were later linked to football hooligans and the far-right group Defend Netherlands.