US intelligence agencies may have been behind the February attack on the North Korean Embassy in Madrid, during which a group of unidentified people broke into the mission, blocked the diplomats and seized computers, El Confidencial reported on Sunday, citing sources, Sputnik reported.

According to El Confidencial newspaper, Spain's National Police and the foreign intelligence unit of the National Intelligence Centre (CNI) are examining all possible versions of what happened. Nevertheless, the sources told the newspaper that the theory that the US intelligence agencies, which could have been acting together with other foreign counterparts, were involved in the attack, was gaining momentum.

CNI reportedly suspects that the way the embassy was attacked resembles the "method of work" of the North American intelligence services during secret operations.

The newspaper added that embassy employees, who were in the building at the time of the attack, told investigators that some attackers spoke Korean and could be nationals of South Korea, a "US strategic ally".