The Spanish Home Office announced on Wednesday evening that Turkish authorities had arrested two Spanish women who "belonged to the Islamic State [and] who were travelling towards Europe with their very young children".

"The two women arrested, for whom the Civil Guard had issued an International Arrest Warrant, had left Ceuta [Spanish North Africa] for Syria in 2014 in the company of their husbands, two notable jihadis who have taken part in dozens of murders, in order to join the terrorist organisation. Since then, they had remained at the epicentre of the territory controlled by the Islamic State as a part of their structures."

Turkish police had been working with Civil Guard intelligence services under the direction of the National High Court in Madrid, the Home Office statement said, adding that the level of "indoctrination in terrorist extremism" the two women had undergone during their time in Syria made them "extremely valuable elements" for the Islamic State in Spain and Morocco.

The Home Office claims Spain's Civil Guard makes "continuous" efforts to control and follow "radicalised" Spaniards who travel to Syria in search of jihad "whilst they remain in these terrorist structures".

"The complex investigation undertaken by Civil Guard Intelligence Service specialists", said the statement, "which has culminated in the arrest of these two people, has taken more than two years during which permanent bilateral cooperation with Turkish security forces and authorities has been key".

The government also said the Civil Guard maintains and "extensive and intense" cooperation with other "allied" intelligence services.

On Tuesday, the Home Office issued a statement saying rumours doing the rounds of Spanish WhatsApp and social networks of an imminent terrorist attack in Spain were false.

On Wednesday, Europa Press reported police had arrested two Spanish men in Madrid—in possession of four AK-47 magazines, but not the weapons—on terrorist indoctrination charges.