British author Frederick Forsyth wasn't always writing. As it turns out, he has also gone undercover and he himself revealed in his recently released memoir "The Outsider: My Life" that he did some spying for British Intelligence agency, MI6 at the height of the Nigerian Civil War and beyond.

Forsyth says that he started working for the MI6 when an intelligence officer asked him to "tell us what's going on" during the civil war. Since then, he has been gathering and sending info to the organization and it went on from 1967 to 1970.

"For the last year of the Biafran War, I was sending... both journalistic reports to the media and other reports to my new friend," Forsyth details as quoted by BBC. He adds that MI6 wanted to confirm if the Nigerian war killed many children and the author corroborated that youngsters died "like flies."

"The Foreign Office was denying that there were any dying children and they were passionate in supporting the dictatorship in Lagos, and it was, oddly enough, MI6 that had a different viewpoint," the author of "The Day of the Jackal" shared.

This revelation shouldn't be a shock to his fans, though. BBC says some of Forsyth's admirers were long under the impression that his extremely lifelike spy novels aren't totally concocted inside his head.

His stories made it sound like he himself was a secret agent and indeed this suspicion prove accurate. During his stint as a spy, he admitted that "there was no fee, no reward, you just do it. It was a different attitude back then."

He, however, had MI6 virtually compensate him for his services by having MI6 approve passages involving the agency he planned to use on his novels. He recalls, via BBC that he got responses such as "Send us the pages and we will vet them, and if they are too sensitive, we will ask you not to continue."

Often times, though, MI6 simply replied with "OK, Freddie!" As per Premium Times, Forsyth does, in fact, owe his experience in the agency some passages in his would-be novels.

He would then go on to become an award-winning author, with his most iconic work "The Day of the Jackal" inspiring a blockbuster movie and earning him a three-book publishing deal.

Despite the success, he still worked for MI6. He was sent out to several regions such as Rhodesia, South Africa and even at East Germany in the midst of the Cold War. His spying gig lasted for two decades.

After his 20-year long stint as a spy, which didn't, however, put him in James Bond level missions, but more on "running errands," he became a full-time author and as perIndependent, Forsyth has sold more than 70 million copies of his novels across the globe.

Other notable works of his included "The Odessa File" and "The Dogs of War."