"Although most of the [attackers] were Korean, at least two of them have been identified by Spanish intelligence services as having links to the US CIA", it said.
Ten individuals who broke into the embassy, before tying up and beating staff as they looked for information on computers, remain at large.
Spanish police and intelligence officers, who are investigating the attack on the North Korean embassy in Madrid in February, believe that US Central Intelligence Agency (CIA) may be behind the incident, El Pais newspaper reported on Wednesday. Not only would it mean that the USA agency had operated on Spanish soil without asking for authorization or informing the authorities, it would also be a violation of the global conventions that protect diplomatic delegations. The operation was perfectly planned as if carried out by a "military cell", sources close to the investigation were quoted as saying by the newspaper.
Last month, 10 masked men stormed the embassy.
Inside, the police reportedly found eight people tied up with bags over their heads.
Kim Hyok-chol, North Korea's most recent ambassador to Spain, played a key role ahead of the summit, leading the negotiating team that received a United States delegation in Pyongyang last month to discuss denuclearisation.
The CIA has denied any involvement, but Spanish government sources said their response was "unconvincing", El Pais said, adding that should the CIA be proven to have been behind the attack, it could lead to a diplomatic row between Madrid and Washington. The hostages were beaten and interrogated.
The diplomat was expelled from Spain in September 2017 over North Korea's nuclear-testing programme.
One of the employees managed to escape and alerted the neighbors, who called the police. Shortly afterwards, the suspects drove out of the embassy in two stolen vehicles and got away, dumping the cars in a street.
He is now Pyongyang's special representative for the US and was involved in preparations for the summit in Hanoi between the North Korean leader and US President Donald Trump. The meeting, aimed at securing North Korea's nuclear disarmament, ended in failure without any agreement on a timetable for disarmament or on future negotiations.