North Korea on Sunday released its first official statement about the break-in at its embassy in Spain last month, calling it a "grave terrorist attack."

A spokesperson of North Korea's Foreign Ministry told the Korean Central News Agency that "an illegal intrusion into and occupation of a diplomatic mission and an act of extortion are a grave breach of state sovereignty and a flagrant violation of international law."

The spokesperson also called for an investigation, saying that North Korea is closely watching rumors that the United States Federal Bureau of Investigation and an anti-North Korea group were behind the raid.

It marks the North's first official response after a group of people broke into the North Korean Embassy in Madrid and made off with computers and documents on February 22nd.

Free Joseon, a mysterious anti-North Korea group, recently claimed responsibility for the break-in and said it shared some of the information obtained from the embassy with the FBI.