Robert Booth, Ewen MacAskill, Duncan Gardhamand Damien Gayle Monday 8 February 2016 08.02 GMT

Kotey and Davis were in gang with Mohammed Emwazi that detained and beheaded western hostages in Syria

A member of the Islamic State cell that oversaw the detention and beheading of western hostages in Syria has been identified as a 32-year-old Londoner, the Guardian has confirmed.

Alexanda Kotey, a convert to Islam who grew up in west London, has been named as part of the British group nicknamed “the Beatles”, which included Mohammed Emwazi.

Emwazi’s kidnap gang has overseen the videoed beheadings of victims including the British aid workers Alan Henning and David Haines, and the US journalists Steven Sotloff and James Foley.

Kotey is described as of Ghanaian and Greek-Cypriot background and his whereabouts are unknown. His fellow west Londoner Emwazi was killed in a drone strike in November.

Another west Londoner, Aine Davis, 31, has also been confirmed as part of the cell. Emwazi, Kotey and Davis, a former drug dealer who went to Syria in 2013, were friends in west London and attended the same mosque.

Davis was detained in Turkey last November on suspicion of planning attacks in Istanbul similar to those in Paris that targeted the Bataclan theatre, the Stade de France and cafes and restaurants.

A spokesman for the Home Office in London would “neither confirm nor deny” that Kotey and Davis were members of Emwazi’s group.

The Washington Post and Buzzfeed identified Kotey earlier on Sunday, citing a US intelligence official. ITV News also named Kotey, as well as confirming that Davis had been part of the terror cell. The Guardian has independently verified the names.

Members of Kotey’s family said in a statement they were “deeply distressed” at the claims and confirmed they had not seen him “for a number of years”.

Kotey is believed to have attended the al-Manaar mosque in Westbourne Park, which was also frequented by Emwazi, who was known widely in the media as “Jihadi John”. A spokesman at the mosque on Sunday said it could not confirm or deny whether the men attended because so many worshippers passed through.

Saleha Islam, director of the al-Manaar mosque, told ITV News: “We are aware that certain people have joined Isis who live in the area of Ladbroke Grove; we have always condemned the actions of these extremists and will continue to do so.

“Al-Manaar is a centre where we have up to 3,000 people attending every week, it is not a membership club and anyone can come and pray. The suggestion that the mosque has radicalised young men shows how ignorant people are of Islam and how mosques work.”

Kotey, known as Alexe, has been described by neighbours in his former west London community as a quiet man who was dedicated to Queens Park Rangers football club.

Believed to be a father of two, the Muslim convert was deemed influential in radicalising young British men who have gone on to join Isis in Syria.

Kotey is believed to have lived in west London until 2009, when he travelled to Gaza in an aid convoy organised by George Galloway, then an MP and now a candidate to become London mayor for the Respect party.

At his former home in west London, where his mother is still believed to live, there was little sign on Sunday of his extremist allegiances. The flat had a Union flag doormat and an upstairs neighbour said Kotey was one of two brothers who had often played with other children in the block. Speaking about his mother, the neighbour said: “She has two boys. She’s a counsellor.”

Galloway on Sunday said he did not know Kotey. “I have never heard of him until today,” he said. “It would appear he was on the list [for the Gaza convoy]. Having looked at his picture, I do not recognise him. Isis did not exist when we took the convoy. The idea that he ran away with the convoy to join Isis … it did not exist then.”

Galloway said no public figure had been as unequivocal as himself in condemning Isis.

“I would shoot them dead with my own hand,” he said.

His spokesman, Ron McKay, added that “there were something like 120 vehicles and around 500 people on [the convoy]. Neither he nor I – as I was also on it – have any recollection of this guy.”

Raised a Greek Orthodox Christian, Kotey converted to Islam as a teenager, it was reported, at which point he met Emwazi.

Buzzfeed spoke to a former friend of Kotey who said he used to run a stall outside the mosque.

“Those guys used to openly preach and argue about what they thought was their cause or ideology,” the friend said. The paper reported the friend saying Kotey advocated suicide bombing, arguing with those who said it was forbidden by the Qur’an.

Two other associates, Choukri Ellekhlifi, 22, of Moroccan origin and from Paddington, and Mohammed el-Araj, 23, from Ladbroke Grove, were both killed in Syria in August 2013. Before he left Britain, Ellekhlifi had been arrested on suspicion of robberies using a stun gun, but was released on bail and was thought to have fled to Syria.

Davis’s wife, Amal el-Wahabi, 27, became the first woman to be jailed for terrorism offences connected to Syria in 2014 after she was caught paying a smuggler to take €20,000 (£15,000) in cash to Turkey for her husband. Sentencing at the Old Bailey, the judge said she “knew he was engaged in violence with guns for extremist religious and ideological reasons”.

The court heard that Davis sent his wife a video of Anwar al-Awlaki, an al-Qaida preacher, proclaiming “martyrdom is a gift and a blessing from the lord of the universe and not a loss”, and another about the shame and disgrace of those who avoided jihad, while an Isis song referred to the machine gun as the “sword of terrorism”.

Londoners Alexanda Kotey and Aine Davis identified as Islamic State 'Beatles' | World news | The Guardian