Saudi Arabia is 'at the top of the list' of countries exporting extremist Islam to the UK, a new report says.

The kingdom has engaged in a 60-year, multi-million dollar campaign to advance its extremist brand of Wahhabi Islam in British Muslim communities, according to a study by the Henry Jackson Society.

This has been achieved through endowment grants to mosques, the funding of Islamic education institutions and the training of imams, the report authors say.

Saudi Arabia is 'at the top of the list' of several Gulf states engaged in an 'intentional and systematic' policy of exporting extremist ideology to the West, a new report claims

The report calls on Theresa May's government to hold a public inquiry into the financing of extremist groups in the UK, after the Home Office said the results of a previous inquiry might never be made public (pictured, Mrs May in Saudi Arabia earlier this year)

'A clear and growing link' can be drawn between this overseas money, which originates in several Gulf states and Iran, and atrocities in the UK and throughout Europe, the society found.

The report identifies what it calls 'an intentional and systematic policy' by these states to 'advance an illiberal and at times anti-Western version of the Islamic religion' in Western countries.

How much money has been allocated to this effort is unknown because the majority of it remains secret, the report admits, but the amount is though to have increased in recent years.

'Indications of the kind of influence that such funding can have... can be seen through the prevalence of Islamist extremist preachers and literature, including the use of Saudi school textbooks,' the report reads.

'This combined with scholarship programmes that bring clerics to Saudi Arabia for training, has gradually contributed to changing the climate of religious belief and practice in many of the West's Muslim communities.

'As well as promoting hardline Wahhabi practices to Muslim communities that formerly identified with other Islamic traditions, this phenomenon has created a challenge for moderate voices and empowered extremists.'

The Henry Jackson Society is calling for a public inquiry into the issue and asks the government to introduce laws forcing Islamic organisations to declare certain types of finance received from overseas, and any conditions placed upon its use.

The Home Office already commissioned a closed-door inquiry into funding for Islamic extremist groups in the UK back in 2015 as part of a Coalition deal to expand airstrikes in Syria and Iraq.

Saudi Arabia has engaged in a 60-year, multi-million dollar effort to export Wahhabi Islam - which forms the basis of extremist ideologies exploited by the likes of ISIS - to the UK, the report says (file image)

It was understood that the report would largely focus on Saudi Arabia, but in May this year the Home Office announced the research has yet to be completed.

Even if the report is finished, the findings may never be made public because of the 'very sensitive' nature of the material, a spokesman said.

Prime Minister Theresa May, who visited Saudi Arabia earlier this year, has been accused of 'kowtowing' to the kingdom by 'suppressing' the report.

Tom Wilson, who wrote the report for the Henry Jackson Society, said: 'There is a clear and growing link between foreign funding of Islamist extremism and the violent terrorism we have witnessed across the UK and Europe.

'The key now is to get ahead of the issue and find out the full extent of what has been going on. A public inquiry would go some way to informing the debate.

'While entities from across the Gulf and Iran have been guilty of advancing extremism, those in Saudi Arabia are undoubtedly at the top of the list.

'Research indicates that some Saudi individuals and foundations have been apparently heavily involved in exporting an illiberal, bigoted Wahhabi ideology.'

A Government spokesman said: 'Defeating the evil ideology of Islamist extremism is one of the greatest challenges of our time.

'The Commission for Counter-Extremism, which the PM announced earlier this year, will have a key role to play in this fight.

'We are determined to cut off the funding which fuels the evils of extremism and terrorism, and will work closely with international partners to tackle this shared global threat, including at the upcoming G20 summit.'

The UK's Saudi Arabian embassy says the claims are 'categorically false'.

Labour MP Dan Jarvis said: 'This report from the Henry Jackson Society sheds light on what are extremely worrying links between Saudi Arabia and the funding of extremism here in the UK.

'In the wake of the terrible and tragic terrorist attacks we've seen this year, it is vital that we use every tool at our disposal to protect our communities.

'This includes identifying the networks that promote and support extremism and shutting down the financial networks that fund it.

'I'm calling on the Government to release its foreign funding report, and guarantee that the new counter extremism commission will make tackling the funding of extremism a priority.'