The London graduate believed to be Islamic State executioner "Jihadi John" once denounced the 9/11 attacks and the 2005 bombings in the British capital, according to an audio recording released Tuesday.
Kuwait-born Mohammed Emwazi was identified by media and experts last week -- and now, reportedly, also by his parents -- as the knife-wielding masked man in online videos showing the beheadings of at least five IS hostages.
In a conversation with a member of British rights group Cage, Emwazi described how in 2009 he was interviewed by a British officer, reported to be from domestic spy agency MI5.
Asked about his views on the New York and London attacks and the war in Afghanistan, Emwazi -- speaking in a London accent -- condemned the loss of life, but complained that his interrogator did not believe him.
"I said, after what I told you, after I told you that what's happening is extremism, this and that, and you're still suggesting that I'm an extremist?" he said.
"And he started going on trying to put words into my mouth to say: 'No you're doing this, this and this, and we're going to keep a close eye on you Mohammed -- we already have been and we're going to keep a close eye on you'."
Cage, which supports people detained in the "war on terror," was in contact with Emwazi for several years, and said MI5 had been tracking him since at least 2009.
Research director Asim Qureshi last week described him as a "beautiful young man" who had been harassed by British intelligence to the point of becoming radicalised.
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Qureshi's comments prompted a furious response among politicians and the media, with the Mayor of London Boris Johnson calling them an "apology for terror."
In the two-minute recording released by Cage, Emwazi said the 2005 London attacks that killed 52 people were the result of "extremism," and noted in Afghanistan, "innocent people are getting killed."
On the 2001 attacks in New York, he said: "If I had the opportunity for those lives to come back then I would make those lives come back. I think what happened is wrong."
Asked what he thought of "the Jews," Emwazi said: "Everyone has got his right to his own beliefs. I don't force no-one."
Meanwhile it was reported that Emwazi's parents have admitted to recognising him when he first appeared in a video showing the execution of US reporter James Foley in August.
Kuwaiti newspaper Al-Qabas said in a report on Monday that Emwazi's father, Jassem Abdulkareem, had been questioned by Kuwaiti police on Sunday and told them his wife "recognised her son's voice," as he subsequently did as well.
The couple last heard from Emwazi in mid-2013 when he called them from Turkey to announce he was going to Syria as an aid worker. "Since then, I've been waiting for news of his death," his father said, according to an unnamed source cited in the report.