HOME Secretary Sajid Javid will not block the execution of ISIS Beatles pair nor the possibility of them being sent to Guantanamo Bay, secret documents have revealed.

According to a letter from Mr Javid to the US Attorney General Jeff Sessions, the minister says Britain will "demand no assurances" on the death penalty for Alexanda Kotey and Shafee El-Sheikh.

The pair, who are accused of belonging to the ISIS Beatles beheading gang alongside Jihadi John, were captured by US backed forces in Syria in January.

In a letter uncovered by The Daily Telegraph it reveals the UK Government has agreed to hand over intelligence to help prosecute the captured jihadists and that Britain will not "formally oppose" the pair being sent to the notorious jail.

According to extracts from the letter highlighted in the newspaper, Mr Javid wrote on June 22, 2018: "I am of the view that there are strong reasons for not requiring a death penalty assurance in this specific case, so no such assurances will be sought."

It goes on to say he has "instructed my officials to set out the terms of our assistance and to work with your officials to action the request".

He spells out that it is a "long held position in the UK to seek death penalty assurances" and that his decision "does not reflect a change in our policy on assistance in US death penalty cases generally" nor the UK Government's "stance on the global abolition of the death penalty".

The pair, from west London, deny being involved in the hostage-taking or beheadings.

The men are alleged to have been part of the ISIS 'Beatles' cell known for its brutality in torturing and killing several American, British and Japanese journalists and aid workers in 2014-15.

The cell's leader Mohammed Emwazi, known as Jihadi John, was killed in a US-led drone strike in 2015 in the formerly held ISIS capital Raqqa, Syria.

The leaked documents also reveal that the Metropolitan Police and FBI have been investigating the two men's activities in Syria for the past four years, with the paper stating more than 600 witness statements being collected in a criminal inquiry involving 14 other countries.

A UK government source told the paper the revelations in the paper had the "potential to be a political nightmare" and that a lot of MPs would be angry with the "idea of British intelligence sending British citizens potentially to their death or to permanent incarceration".

According to reports Mr Javid believes this country may not be robust enough to ensure a successful prosecution and that American terrorism laws are more effective.

Extracts state: "In light of this, the UK does not currently intend to request, nor actively encourage, the transfer of Kotey and El-Sheikh to the UK to support a future UK based prosecution."

Since their capture there has been a debate over where and how the pair should be prosecuted with families of victims calling for a fair trial whether in the UK or the US.

A Home Office spokeswoman said they do not comment on leaked documents and added: “We continue to engage with the US Government on this issue, as we do on a range of national security issues and in the context of our joint determination to tackle international terrorism and combat violent extremism.

"The UK Government’s position on Guantanamo Bay is that the detention facility should close.”