A recording has emerged in which the Islamic State fighter Mohammed Emwazi denied being an extremist and complained about UK security services.
In the tape, Emwazi - known as "Jihadi John" - said MI5 had threatened him and tried to "put words into my mouth".
The tape was made in 2009 by advocacy group Cage after Emwazi was deported from Tanzania and questioned by MI5.
The Kuwait-born Briton is believed to have taken part in the beheadings of Western hostages by Islamic State (IS).
In emails and a meeting with Cage, Emwazi said he had arrived in Tanzania for a safari holiday in 2009 but had been refused entry and was put on a flight to Amsterdam, where a British agent accused him of trying to reach Somalia for terrorism training.
Speaking to Cage when he returned to London later that year, Emwazi said: "He [the MI5 officer] looked at me and he said 'I still believe that you're going to Somalia to train'.
"I said 'after what I just told you, after… I told you that what's happening is extremism… you're still suggesting that I'm an extremist?'
"He just started, you know, going on trying to put words into my mouth."
Emwazi said MI5 officers had been "threatening" him and told him: "We're going to keep a close eye on you Mohammed, we already have been."
He said the agent - who called himself Nick - also asked him what he thought of 9/11, the war in Afghanistan and the 7 July attacks in London.
Emwazi replied "innocent people" had been killed in the 7/7 attacks and it was "extremism". He also said what happened on 9/11 was "wrong".
"What do you want me to say?" he said he told Nick. "If I had the opportunity for those lives come back then I would make those lives come back."
Cage's research director Asim Qureshi made the recording on a Dictaphone. The excerpt is part of a longer recording, not all of which was made available to the BBC.
Mr Qureshi has been criticised after suggesting MI5 harassment could have contributed to the radicalisation of Emwazi.
But he told BBC Radio 4's Today programme on Tuesday: "All we are asking for is a little bit of accountability.
"What we want to see is that our security agencies don't operate in a way that actually drives people away from feeling like they have a role to play in this society."
Mr Qureshi said Cage was "horrified" by Islamic State's killings and insisted his comments were "not about sticking up for" Emwazi.
Jihadi John was unmasked as 26-year-old Emwazi last week, although British and US security services have reportedly known his identity for some time.
Jihadi John, a nickname coined by the British press, has been seen in several videos showing the apparent murders of Islamic State captives, including British aid workers David Haines and Alan Henning.
Emwazi's parents, who live in Kuwait, are said to have told the authorities there that they last spoke to their son in 2013 when he called them from Turkey.
They said he told them he was going to do humanitarian work in Syria.
Emwazi's mother is said to have told Kuwaiti officials she immediately recognised his voice when she heard him on a hostage video.
Kuwaiti officials have told the BBC the family has been taken to a safe house.
They also said when the news about Emwazi broke, his father took an indefinite leave of absence from his job at a supermarket.
Emwazi was born in Kuwait in 1988 and came to the UK in 1994 when he was six years old.
He was educated at the Quintin Kynaston Community Academy in St John's Wood, north London, and then graduated from the University of Westminster in 2009 with a computing degree.