Thirteen websites used to spread terrorist propaganda online have been targeted in two parallel Europol-coordinated operations this week, the body announced on Friday.

Sites linked to Islamic State, al-Qaida and its affiliates, as well as the Syria-based rebel group Hay’at Tahrir al-Sham were referred for removal under European Union laws as part of a yearlong operation involving 10 law enforcement authorities across the continent.

The EU laws require hosting service providers to remove the content within an hour of receiving a removal order, or face a penalty determined by the individual member state. 

“Servers were taken down in Germany, the Netherlands, United States and Iceland,” stated Europol, while nine “radicalized individuals” were arrested in Spain.

Another operation led by Spain’s Guardia Civil tackled media linked to the Islamic State’s I’LAM Foundation which Europol said ran “communication channels, such as radio stations, a news agency and social media content” with a global reach.

“They communicated directives and slogans of Islamic State in over thirty languages, including Spanish, Arabic, English, French, German, Danish, Turkish, Russian, Indonesian and Pashto,” stated Europol.

Several terabytes of information were uncovered by investigators which will now be used to inform law enforcement investigations into the terror group.

It comes as the overall terrorist threat to the European Union remains “acute” with jihadist terrorism a principal concern.

Europol stated its operations followed the seizure of four computer servers in Romania, Ukraine and Iceland as part of ongoing investigations into both religious and politically-motivated terrorist groups.

The sites were used to “enable terrorist organizations and violent extremists to bypass the enhanced moderation and content removal efforts of mainstream online service providers, allowing them to maintain a persistent online presence,” according to Europol.

Alongside inciting violence and spreading propaganda, the sites were used for recruitment and fundraising. The content included “manuals for creating explosives and propaganda designed to radicalize and mobilize individuals.”