Madrid, Oct. 24 -- European security agencies have been placed on high alert after Spanish authorities uncovered jihadist calls urging extremists to launch suicide bombings and vehicle attacks against police and demonstrators during widespread economic protests across Europe, according to a report by Euronews citing El Pais.

The Portuguese Internal Security System (SSI) confirmed it is "closely monitoring" the threat. In a statement issued to the Lusa news agency, the agency noted, "The Secretary General of the Internal Security System is closely monitoring the situation mentioned [jihadist calls for attacks against police and demonstrators] within the scope of her responsibilities and in constant coordination with the relevant authoriti...