(Bloomberg) -- An employee at the Ukrainian embassy in Madrid suffered minor injuries when a letter bomb exploded on Wednesday, according to Spain’s Interior Ministry. 

After the envelope arrived to the embassy, the employee “started to open it and an explosion happened,” Ukranian Foreign Minister Dmytro Kuleva said.  The injured employee received medical attention and “he has already returned to the embassy.”

The attack “is very serious. It is an attack at the diplomatic office, which is protected by international law,” Kuleba said. “The Spanish police is investigating. I ordered all diplomatic offices to increase protection. We will protect all Ukrainians not only in Ukraine but also abroad.”

(Updates with Kuleba comments from paragraph two)

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