London-born Bary was initially suspected of being “Jihadi John” and police say he represented a “high danger”.
A former London rapper has been arrested on suspicion of joining Islamic State fighters in Syria.
Abdel-Majed Abdel Bary was arrested on Monday in southern Spain, according to The Associated Press, which cited two sources close to the investigation.
Bary was initially suspected of being “Jihadi John”, the Islamic State member who appeared in a video of the murder of American journalist James Foley.
The real Jihadi John turned out to be Mohammed Emwazi but Spain’s National Police still described Bary as “one of the most sought terrorists in Europe, both because of his criminal trajectory in the ranks of Daesh and because of the high danger that he represented”.
The police statement did not name Bary but described the suspect as an Egyptian who left Europe to fight in Syria.
Police believe Bary, 29, was on his way home from the Middle East when he was arrested along with two other men at an apartment in Almeria. The group will appear before a National Court judge in Madrid on Wednesday.
Bary grew up in London and used the names Lyricist Jinn and L Jinny as a rapper, doing songs about drug use, violence and his experience as an asylum-seeker in the UK.
He is believed to have become radicalised after his father Abdel Abdul Bary was extradited to the US in 2012.
The older Bary was convicted of charges relating to the 1998 bombings of US embassies in Kenya and Tanzania, which killed 224 people. He was jailed in 2015 for 25 years.
In 2014 a photo of the younger Bary was posted on Twitter, showing him holding severed head.
In 2015, a Spanish woman María de los Angeles Cala Marquez was arrested in Madrid as she tried to travel to Turkey on a fake passport.
She had been on her way to Syria to meet and marry Bary, who she said she had fallen in love with while talking to him online.
Shiraz Maher, an expert on radicalisation at King’s College London, described Bary as one of the earliest “foreign fighters” to have become disillusioned with Islamic State.
Mr Maher said: “He was known to have been disillusioned for quite a while, and he then just disappeared off the radar.
“He was a member of ISIS and clearly participated in all kinds of horrors the group was involved in and should face punishment for those crimes but, at this stage, he is more likely to be someone who was trying to save himself in Spain.”
The UK Foreign Office has declined to comment on the case.