Investigations into the case began in February when the 27-year-old suspect was arrested on sexual harassment charges in Gandía, Valencia.
Officers then found evidence of child pornography, indecent exposure and sexual taunting of minors on his computer, newspaper 20 Minutes reported.
The suspect pretended to be a minor on social media websites, befriended his victims and then encouraged them to send him pictures of them naked by showing them pornographic content.
This practice is known as child grooming.
Police are currently interviewing a large number of children who spoke to the alleged sexual predator, with approximately 300 minors thought to have been harassed.
The suspect was taken into custody on March 25th but Valencia's public prosecutor had to release him temporarily on Tuesday as police failed to produce the suspect's hard drive during a preliminary hearing on the matter.
The news comes only two weeks after Spain's biggest ever paedophilia scandal, in which a karate champion in Gran Canaria was handed a 302-year sentence for raping dozens of pupils at his martial arts school.