Nero Saraiva, 28, is thought have risen in the ranks to become one of ISIS's most senior fighters and has been posting images of firearms similar to those used by "Jihadi John" on social media.

Saraiva is one of five young men from east London who all moved from their native Portugal to London and adopting extremist views and travelling to Syria to join the terrorist network's ranks.

The men, who lived in Leyton and Walthamstow, have long been on the radar of intelligence officials - who believe the group plays a vital role in the production and dissemination of the sick beheading videos featuring Jihadi John, Daily Mail reports.

Saravia, a father-of-four has posted several images of weapons on his Twitter, including a Glock 19 pistol with an extended magazine, similar to that carried by Jihadi John, the Sunday Times reports.

Ringleader Saraiva, a former engineering student was the first of the group to travel to Syria in the summer of 2012.

Saraiva was the first of the group to travel to Syria in the summer of 2012 and is thought to have lived in the UK for the longest

Last year his name was linked to an alleged terrorist plot in east Africa involving al-Qaeda affiliate group al-Shabaab.

He is a known supporter of hate-preaching cleric, Abu Hamza, recently jailed for life in America for terrorism offences.

In July 2014 - 39 days before James Foley became the first Western hostage to be murdered - he posted a message on Twitter indicating he had advance knowledge of the American journalist's grisly fate.

Saraiva tweeted: 'Message to America, the Islamic State is making a new movie. Thank u for the actors.'

Just over a month later James Foley was beheaded in a YouTube video entitled A Message To America.

European security officials believe Saraiva and his East London cell are responsible for the filming and dissemination of the series of sickening beheading videos, including the execution of British hostages Alan Henning and David Haines.

MI5 are said to have worked out the identity of Jihadi John but have not yet released his name.

All five of the football-playing jihadists showed a passion for football in their younger years, and after moving to the UK, would often meet in a Portuguese-run cafe in east London to watch matches.

It is still unclear how they were radicalised in Britain but the borough of Waltham Forest where they lived is known to be home to a number of extremists. 

Fabio Pocas, the youngest member of the group

Also among the five, who all moved to London over the space of several years to study or find work, is Fabio Pocas, the youngest member of the group at 22.

Pocas moved from Lisbon to London in 2012 in his bid to become a professional footballer.

He had previously played at the youth academy of Sporting Lisbon - a club which has bred a host of world stars including Luis Figo and Cristiano Ronaldo.

After arriving in London, Pocas began playing for an amateur league team called UK Football Finder Football Club (UKFFFC), where he flourished.

After helping the side become champions of their division, he was offered the prospect of a trial with a professional club.

The team's coach, Ewemade Orobator, told The Sunday Times: 'He came here to play football seriously.

'In about May 2013 an agent came down and said "Work hard over the summer and I will get you a trial [with a professional club]".'

But Pocas, failed to capitalise on the offer and simply 'disappeared' - before later resurfacing in Syria in ISIS propaganda photos.

The talented footballer has since been prolific on social media, posing in online pictures with ISIS flags and guns.

He now goes by the name Abdurahman Al Andalus and lives in a town called Manjib with his Dutch teenage jihadi bride.

In a recent Facebook message, he wrote: 'Holy war is the only solution for humanity.'

All five of the men had family roots in Portugal's former African colonies and some were brought up to be Christians.

They travelled to London separately but at one point, a few of them shared a flat in Leyton, according to Expresso newspaper in Lisbon.

Celso Rodrigues da Costa followed his older sibling Edgar to Syria to join ISIS.

Celso Rodrigues da Costa, 28, is believed to have had training sessions with Arsenal - but was not offered a contract by the club.

However an Arsenal spokesperson said: “We don't have any record of a Mr Celso Rodrigues Da Costa being involved with the club at any level.”

Last April, he was seen in an ISIS video shot on the banks of the Euphrates in Syria with an AK-47 in hand.

In the clip, he slammed the West and denounced school teachers as 'drug dealers and paedophiles'.

Celso is thought to have followed his older brother, Edgar, to Syria in 2012.

His 31-year-old sibling, who studied management and accounting in Portugal before emigrating to London, is thought to leading a band of foreign militants in Aleppo.

Both men were enrolled at the University of East London (UEL) in Stratford, but were thrown off their courses after failing to attend lectures. 

The fifth member of the cell, a 26-year-old former Catholic known as Sandro, was the last to travel to Syria and was reportedly killed last October in a coalition airstrike.

European security officials believe the East London cell are responsible for the filming and dissemination of the series of sickening beheading videos featuring British executioner Jihadi John, seen here in a video released last night allegedly showing the beheading of Japanese hostage Kenji Goto