Abdellatif Aoulad Chiba, from Morocco, was arrested after it emerged he had been attempting to recruit members to carry out a terrorist attack involving the contamination of water supplies, according to the Spanish Interior Ministry.
The accused was operating a radical website which was used to spread propaganda and encouraged people to convert to Islam.
The Ministry alleges the website also provided training and guidance for new recruits, encouraged terrorist activity and provided links to media produced by Islamic terror groups.
Chiba is understood to have been involved in terrorist activity in the past, which had resulted in him being expelled from Jordan.
The Royal Gibraltar Police is keeping a close eye on developments and is being kept ‘in the loop’ by the Spanish authorities.