Authorities later identified the Turkish national as Cengiz Yalcin, and the others are Ahmad Avar and Muhammad Adamov.

CNN: Judge in Spain takes statements from terror suspects

Adamov, the other Chechen, had received explosives training in Afghanistan, where he become an expert in managing explosives and may have participated in a recent bomb attack in Moscow, according to Spanish authorities.

CNN: Spain 'al Qaeda cell' may have targeted Gibraltar

Two Chechen-Russians -- Eldar Magomedov (also known as Ahmad Avar) and Muhammad Adamov -- whom Spanish security services suspect had been tasked with carrying out an attack, were arrested on a bus travelling towards France.

CNN: Spain 'al Qaeda cell' may have targeted Gibraltar