According to Spanish press, the explosive mechanism in the package was supposed to blow up in the ministry and could be activated if someone pulled the rope on it, Sputnik reported.
It is already the fifth explosive package sent to different organizations in Spain. Earlier in the day, Spain's Torrejon de Ardoz air base received a similar suspicious package, with another envelope containing a "pyrotechnic substance," which was sent to Prime Minister Pedro Sanchez, intercepted by the police.
On Wednesday, Spanish press reported that an employee of the Ukrainian embassy in Madrid was slightly injured in the explosion of a device hidden in a mail envelope around 1:00 p.m. local time (12:00 GMT). The employee was reportedly taken to a hospital.
Ukrainian Ambassador to Spain Sergei Pohoreltsev later said it was a package with documents that exploded near the embassy rather than an envelope.
Later that day, Spanish arms firm Instalaza, based in the city of Zaragoza, received a package similar to the one that exploded near the Ukrainian embassy.
Spanish media reported, citing sources, that the Spanish National Court was set to initiate trial proceedings after receiving a report on what happened from the police, with the judge considering the incident as a terrorist offense.