Spanish police arrested four people on the outskirts of Madrid on Tuesday accused of promoting Islamist militancy via social media, the Interior Ministry said.
Three of those detained in the operation, which is ongoing, were from Morocco and the fourth was Spanish, it said in a statement.
They allegedly targeted hundreds of people via instant messaging and other social media before making direct contact with smaller groups.
Including Tuesday's arrests, Spain has detained 23 people so far this year with presumed links to Islamist militancy.
