“Since the 1960s, Saudi Arabia has sponsored a multimillion-dollar effort to export Wahhabi Islam across the Islamic world, including to Muslim communities in the west,” the British society’s report said.

“In the UK, this funding has primarily taken the form of endowments to mosques and Islamic educational institutions, which have in turn played host to extremist preachers and the distribution of extremist literature. Influence has also been exerted through the training of British Muslim religious leaders in Saudi Arabia, as well as the use of Saudi textbooks in a number of the UK’s independent Islamic schools.”

It adds, “A number of Britain’s most serious Islamist hate preachers sit within the Salafi-Wahhabi ideology and are linked to extremism sponsored from overseas, either by having studied in Saudi Arabia as part of scholarship programmes, or by having been provided with extreme literature and material within the UK itself.”

The report has further urged the UK government to consider requiring religious institutions, including mosques, in Britain to be required to reveal sources of overseas funding.

The findings come as Theresa May faces pressure to publish the government’s own report into foreign funding of terrorism. The Home Office-led report was completed six months ago, and No 10 says ministers are still deciding whether to publish. MPs nervous of upsetting strategic relations in the Persian Gulf have also decided not to publish a separate Foreign Office strategy paper on the region.

Saudi Arabia is likely to be angered by the findings since its dispute with Qatar has largely been based on the accusation that its Persian Gulf rival is both the primary funder terrorism overseas and harbours terrorists that support the Muslim Brotherhood or Hamas.

The report, cited by The Guardian, has stressed that the level of funding of Wahhabism has been on the increase.

It claims in 2007 Saudi Arabia was estimated to be spending at least $2bn (£1.5bn) annually on promoting Wahhabism worldwide. By 2015 that figure was believed to have doubled.

The impact of this increased spending may well have been felt in Britain: in 2007, estimates put the number of mosques in Britain adhering to Salafism and Wahhabism at 68. Seven years later, the number of British mosques identified with Wahhabism had risen to 110.

It argues that Saudi Islamic charitable groups have tended to fund Wahhabist ideology. Some of Britain’s most prominent extremist preachers — such as Abu Qatada, Abu Hamza, Abdullah al Faisal and Sheikh Omar Bakri — have all sat within what can be described as a broadly Wahhabi/Salafi ideology, the report says. In 2014, it was estimated that Britain’s Salafi Mosques had a collective capacity for a 44,994-strong membership.

The report concludes, “The attempt by several states to influence Islamic communities and advance an illiberal – and at times anti-western – version of the Islamic religion appears to have been an intentional and systematic policy, with the level of funding allocated to this effort believed to have grown in recent years.

“While some of this financing appears to originate from private individuals and independent foundations, research by the German intelligence agencies and others has pointed to these foundations being closely linked to governments of several Persian Gulf states.”