"The structure [to which the detained are believed to be connected] used assumed identities to send funds to managers of the economic apparatus of Daesh in Syria and Iraq that were used for operational finance in conflict zones," the ministry said in a statement.
According to the statement, the two brothers, both of Moroccan origin, had a third brother who was also involved in the scheme and who had moved to Syria with his family and children. He subsequently died there but the illegal Daesh funding did not stop.
The ministry stressed that the unmasking operation was the first in Spain which provided concrete evidence of such finance operations.
Earlier in the day, Italian law enforcement arrested two Moroccans in the north of the country for allegedly recruiting new members for the terrorist group, outlawed in many countries including Russia.