The British government will order a crackdown on the Muslim Brotherhood and a network of Islamist groups accused of fuelling extremism in Britain and across the Arab world, The Telegraph reported on Sunday.

Prime Minister David Cameron launched an inquiry into the Brotherhood earlier this year, prompted by concerns it was stoking an Islamist ideology that had encouraged British jihadists to fight in Syria and Iraq.

Sir Richard Dearlove, the former head of MI6 who is an adviser to the review, is reported to have described it as “at heart a terrorist organization”, according to The Telegraph. A senior source close to the inquiry said its report – compiled but not yet published – had identified “an incredibly complex web” of up to 60 organizations in Britain, including charities, think tanks and even television channels, with links to the Muslim Brotherhood, which will all now come under scrutiny.

The inquiry, aided by the security services, has also investigated its network abroad. One expert said that the Brotherhood was now operating from three major bases – London, Istanbul and Doha, the capital of Qatar.

Dr. Lorenzo Vidino, who is understood to have worked on the Cabinet Office report, said, according to The Telegraph, “It is clear that the Brotherhood has many dark spots, ranging from its ambiguous relationship with violence to its questionable impact on social cohesion in Britain.”

The Government crackdown will stop short of outlawing the Muslim Brotherhood but action is expected to include: Investigations into charities that are effectively “fronts” for the Brotherhood; Inquiries into funding of the organization and links to jihadi groups abroad; Banning clerics linked to the group from countries such as Qatar and Turkey from coming to Britain for rallies and conferences.

The source told The Telegraph, “We cannot ban the organization, but that was never the intention of the review. We can go after single individuals, not for terrorist-related activity, but through the Al Capone method of law-enforcement. We cannot get them for terrorism but I bet you they don’t pay their taxes.”

“One of the big things is piling pressure on the charitable missions. Until now it has been very hard to monitor all the groups linked to the Muslim Brotherhood.”

It is understood the Government will also use powers already available to Theresa May, the Home Secretary, to bar radicals linked to the Brotherhood. Visiting clerics from Turkey and Qatar are of special interest.

The Muslim Brotherhood rose to power in Egypt following the ouster of former President Hosni Mubarak. However, its president Mohammed Morsi was himself ousted by the military last year.

Since Morsi’s ouster, the Muslim Brotherhood has been the subject of a broad crackdown, which has seen thousands of Brotherhood supporters jailed.

Morsi himself is currently on trial in several cases. In one trial he is being accused of inciting the killings of opposition protesters outside the presidential palace in December 2012.

In another trial, Morsi and 35 others, including leaders of the Muslim Brotherhood, are accused of conspiring with foreign powers, the Hamas terror group and Iran to destabilize Egypt.

Another of Morsi’s trials, which began in January, cites his role in a 2011 jailbreak which saw the deaths of several police officers. A fourth trial will be held over charges of insulting the judiciary. 

In addition to these trials, Egypt recently charged the ousted president, along with several other people, with endangering national security by leaking state secrets and sensitive documents to Qatar, a known sponsor of the Muslim Brotherhood. The governments of Saudi Arabia, Bahrain, and the United Arab Emirates recently withdrew their ambassadors from Qatar, in protest over Qatar’s support for the Muslim Brotherhood, especially in Egypt.