When first revealed, Morten Storm's account of his life as a double agent inside al Qaeda sent shockwaves through Denmark's political and intelligence establishment. The first accounts came in the Danish newspaper Jyllands-Posten in October 2012.

In those articles, and in his new memoir "Agent Storm: My Life Inside al Qaeda and the CIA," which we co-authored, Storm recounted how after being recruited by Danish intelligence agency PET, he helped the CIA target several al Qaeda terrorists for assassination, most notably the American terrorist cleric Anwar a-Awlaki, who was killed in a CIA drone strike in September 2011.

The allegations have proven explosive in Denmark, where it is illegal for the government to take part in targeted killings.

Storm says his Danish handlers set up and attended meetings he had with the CIA in Denmark and overseas at which plans to track down terrorists were set in motion. He says Danish intelligence was fully aware the Americans planned to use lethal force.

Storm has significant corroborating evidence to back up his claim. He provided us with several hours of secret iPhone recordings of meetings and phone calls with his Danish and American intelligence handlers during which several of the kill missions were discussed.

CNN has not been able to independently authenticate the recordings, but the time the electronic files were first created were consistent with his account.

One of the recordings was of a meeting he says was set up with his PET and CIA handlers at a Danish resort a week after al-Awlaki was killed. On the tape, Storm makes clear to an American interlocutor that he and Danish intelligence had been key to getting al-Awlaki:

"We took initiative to create this because the Americans failed in their attempt to hit Anwar, they failed in their attempts to trace Anwar al-Awlaki, the Americans have failed in every single attempt to arrest or kill Anwar al-Awlaki, except when we went in, we traced him down again, created contacts with him, now he is dead, because of the work we have done."

In the same recording, the American can be heard telling Storm that President Barack Obama knew about his contribution to the al-Awlaki mission, "We had our whole project going forward -- of which you played the highest role,' he said.

But the American denied Storm provided the critical breakthrough, frustrating Storm, who told CNN he had been promised $5 million if he led the CIA to the terrorist cleric. It was after this meeting he first made contact with the Danish newspaper.

After Jyllands-Posten first broke the story, PET refused to confirm or deny Storm's claims. "Out of consideration for PET's operational work, the PET neither can nor will confirm publicly that specific persons have been used as sources by the PET," it said.

"However, the PET does not participate in or support operations where the objective is to kill civilians. The PET did therefore not contribute to the military operation that led to the killing of al-Awlaki in Yemen," then-PET director Jakob Scharf stated.

Neither PET nor the CIA responded to CNN's requests for further comment.

Storm's revelations led Danish parliamentarians to demand new oversight rules for PET.

In January 2013, Storm met with several of them in Copenhagen. Denmark's Ministry of Justice announced it would set up a supervisory board to oversee the Danish intelligence agency, without acknowledging Storm was the reason. Then-Justice Minister Morten Bodskov said the new board would strike "the right balance that will ensure that we have an effective intelligence agency and a good rule of law."

But the government resisted calls from opposition MP's for a full parliamentary inquiry.

After the publication of another Jyllands-Posten article in March 2013, with fresh evidence retrieved from Storm's cell phones, Storm's account received heavyweight backing from Denmark's former spy chief.

Hans Jorgen Bonnichsen, Scharf's predecessor as head of PET, told Danish television that the corroborating evidence presented in the Danish media suggested the PET had used Storm to track down terrorist operatives overseas to help the U.S. target them for assassination. Bonnischen was at the helm of the intelligence agency in the period before Storm says he was recruited as an agent.

In late 2013, a political scandal forced the resignations of PET Director Scharf and Interior Minister Bodskov after it emerged Scharf had instructed subordinates to obtain information on the movements of a Danish MP.

(CNN)