A letter bomb sent to Spanish Prime Minister Pedro Sánchez was intercepted on November 24.
The Spanish interior ministry said four envelopes have now been sent containing “pyrotechnic material.” One exploded Wednesday at the Ukrainian embassy in Madrid, injuring a staffer.
The interior ministry said in a statement that the letter bomb to Sánchez was delivered by regular mail and was “similar in its characteristics and content to those received by the Ukrainian Embassy in Madrid, by the company Instalaza in Zaragoza and by the Torrejón Air Base.”
Spanish arms company Instalaza, which manufactures the grenade launchers that Spain has provided to Ukraine, also received a letter bomb on Wednesday, which was detonated by the police.
Another letter bomb was sent to the Satellite Centre of Torrejón de Ardoz air base on Thursday and was detected by security forces before it could do any damage.
The interior ministry said it had ordered the “National Police and the Civil Guard to take extreme measures to protect public administrations and buildings, especially with regard to controls on postal deliveries.”