Spanish Interior Minister said in a statement that nine suspects were arrested during a security operation on Wednesday over having links to PKK terrorist organisation.
"The police operation was against the structure of education, training and integration in military apparatus of the terrorist organisation PKK-KCK, which operates in Turkey and Syria." the ministry said.
During ongoing operation, police also searched 11 houses in dawn raids in Madrid, Valencia and Bilbao, the ministry added.
Turkey has long been confronted with armed attacks in its southeastern and eastern regions by the PKK, which was founded in 1974 by Abdullah Ocalan and his supporters in Ankara.
Armed clashes and acts of violence have continued on and off for over 30 years and have claimed the lives of over 40,000 people.
PKK, which is considered a terrorist organisation by Turkey, the US, and EU resumed its 30-year armed campaign against Turkey in late July, 2015, after unilaterally ending a two and half year ceasefire.
Since then, more than 250 people; including, security officials and civilians have died in PKK terror attacks.