According to media reports, Spanish officials said that the suspects arrested include a Turk origin man while the other two were Chechen Russians.
The El Pais newspaper said the Turkish engineer, Cengiz Yalcin, was a paraglider and model aeroplane enthusiast and was learning how to fly.
The two Russians – Eldar Magomedov, said to be a former member of Soviet Union Special Forces, and Mohamed Ankari Adamov – were learning how to pilot a small plane.
Madrid daily newspaper La Razon said Magomedov, considered by Western secret services as one of the most dangerous Al Qaeda, was a highly trained expert in making car bombs, carrying out attacks with aircraft and in trains and underground rail systems.
Yalcin asked his paragliding instructor for aerial photographs of a shopping mall in Gibraltar whatever it cost him.
Investigators found a video where Yalvin is seen flying a remote-controlled plane.
The terror group was not specified, but Spanish authorities said it was Al Qaeda.
Evidence provided by Russia confirmed Magomedov with international terrorist organisations and that he had been in Pakistan and Afghanistan in 2010.
Magomedov sometimes acted under the false name “Muslin Dost”.
Both men entered Spain in April or May and allegedly took paragliding lessons. They were allegedly heading to France when police arrested them in Ciudad Real city.
Neither had any identification documents but each is known by several assumed names.