Registration forms detailing phone
numbers and family contacts are handed to Sky News by a disillusioned convert
to the group.
Nationals from at least 51 countries, including the UK,
had to give up their most personal information as they joined the terror
organisation.
Only when the 23-question form was filled in were they
inducted into IS.
A lot of the names and their new Islamic State names on
the registration forms are well-known.
Abdel Bary, a 26-year-old from London joined in 2013
after visiting Libya, Egypt and Turkey.
His whereabouts are unknown.
Another jihadi named in the documents, now dead after
being targeted in a drone strike, is Junaid Hussain, the head of Islamic
State's media wing who along with his wife former punk Sally Jones, plotted
attacks in the UK.
Her whereabouts are unknown.
Reyaad Khan from Cardiff, who also entered in 2013, is
also among those found among the registration forms.
He was well known for appearing in a highly produced
Islamic State propaganda video.
He was later killed.
But the key breakthrough from the documents is the
revealing of the identities of a number of previously unknown jihadis in the
UK, across northern Europe, much of the Middle East and North Africa, as well
as in the United States and Canada.
Their whereabouts are crucial to breaking the
organisation and preventing further terror attacks.
Many of the men passed through a series of jihadi
"hotspots" - such as Yemen, Sudan, Tunisia, Libya, Pakistan and
Afghanistan - on multiple occasions, but were apparently unchecked, unmonitored
and able to both enter Syria to fight and then to return home.
One of the files marked "Martyrs" detailed a
brigade manned entirely by fighters who wanted to carry out suicide attacks and
were trained to do so.
Some of the telephone numbers on the list are still
active and it is believed that although many will be family members, a
significant number are used by the jihadis themselves.
The files were passed to Sky News on a memory stick
stolen from the head of Islamic State's internal security police, an
organisation described by insiders as the group's SS.
He had been entrusted to protect the organisation's core
secrets and he rarely parted with the drive.
The man who stole it was a former Free Syrian Army
convert to Islamic State who calls himself Abu Hamed.
Disillusioned with the Islamic State leadership, he says
it has now been taken over by former soldiers from the Iraqi Baath party of
Saddam Hussein.
He claims the Islamic rules he believed have totally
collapsed inside the organisation, prompting him to quit.
I met him in a secret location in Turkey, and he said IS
was giving up on its headquarters in Raqqa and moving into the central deserts
of Syria and ultimately Iraq, the group's birthplace.
He also claimed that in reality Islamic State, the
Kurdish YPG and the Syrian government of Bashar al Assad, are working together
against the moderate Syrian opposition.
Asked if the IS files could bring the network down he
nodded and said simply: "God willing".
From the attacks in Tunisia and the Bataclan massacre in
Paris, it is clear that IS is refocusing its base of operations abroad and is
intent on carrying out high-profile attacks in Western countries, something that security chiefs across Europe are warning about
right now.
Sky News has informed the authorities about the
haul.
Thursday 10 March 2016