MADRID (Reuters) - Spanish police arrested nine people on Wednesday accused of belonging to and collaborating with a criminal and terrorist organization due to connections with the Kurdistan Workers Party (PKK), the Interior Ministry said in a statement.

The PKK, which is fighting for autonomy for Turkey’s Kurds, is considered a terrorist group by Turkey, the United States and the European Union. The decades-long conflict has cost more than 40,000 lives.

Of those arrested, eight were from Spain and one from Turkey, according to the statement.

The operation, which remains open, also searched 11 houses during dawn raids in Madrid, Valencia and Bilbao, the ministry said.

“Those arrested, in collaboration with other residents in other European countries, supplied the necessary infrastructure to send people to join the ranks of the People’s Protection Units (YPG) or the armed wing of the organization,” the ministry said.

Including the arrests on Wednesday, Spain has detained 19 people accused of belonging to the PKK since 2013, according to the ministry.