The government has been criticised for refusing to publish an internal report on the funding of UK extremist groups.
The home secretary has published a two-page summary which concluded most organisations were funded via small, anonymous British-based donations.
Amber Rudd said she had decided to do so for national security reasons.
Opposition parties claimed the report was being “suppressed” to protect Saudi Arabia which has been accused of being a source of extremist funding.
The Home Office has been under pressure for months to publish its investigation into how Islamist extremist groups in the UK are funded.
Ms Rudd said she would not be making the report public for national security reasons and because of the personal information it contained.
Some MPs will be allowed to view the report in private but without revealing its contents.
Instead, the summary of the report concluded that most extremist organisations got their money, often hundreds of thousands of pounds, from individual donors in the UK.
It also confirmed that a small minority did get significant funds from overseas. These, it said, taught “deeply conservative forms of Islam” to individuals who became “of extremist concern”.
From now on, charities will have to declare any overseas funding to the Charity Commission.
The summary said: “The most common source of support for Islamist extremist organisations in the UK is from small, anonymous public donations, with the majority of these donations most likely coming from UK-based individuals.
“In some cases these organisations receive hundreds of thousands of pounds a year.”
But it added: “For a small number of organisations with which there are extremism concerns, overseas funding is a significant source of income.
However, for the vast majority of extremist groups in the UK, overseas funding is not a significant source. Overseas support has allowed individuals to study at institutions that teach deeply conservative forms of Islam and provide highly socially conservative literature and preachers to the UK’s Islamic institutions.
“Some of these individuals have since become of extremist concern.”
The government’s refusal to publish the full report angered opposition parties which accused ministers of trying to protect allies such as Saudi Arabia which has long been accused of being a source of extremist funding, something it has long denied.
The Green Party co-leader Caroline Lucas said there was a deep complicity between Whitehall and Riyadh.
She said: “The statement gives absolutely no clue as to which countries foreign funding for extremism originates from – leaving the government open to further allegations of refusing to expose the role of Saudi Arabian money in terrorism in the UK.”
The Lib Dem leader, Tim Farron, said the government was putting its friendship with Saudi Arabia ahead of its values.
He said: “What we want to know is who are the violent extremists and who are their funders.
“This report clearly has found some of that out and we’re bound to start suspecting all the more now that the sources of funding must be from the likes of Saudi Arabia, Qatar, otherwise the government wouldn’t be so embarrassed that they won’t tell us the truth.”
Shadow home secretary Diane Abbott, said: “There is a strong suspicion this report is being suppressed to protect this government’s trade and diplomatic priorities, including in relation to Saudi Arabia. The only way to allay those suspicions is to publish the report in full.”
Cutting off the funding
The Home Office insisted diplomatic relations played no part in the decision not to make the full report public.
In a blog published on its website, the Home Office said: “The former prime minister [David Cameron] was clear when committing to the review in the House that it would report to the home Secretary and prime minister.
No commitment was made to publish the review… Contrary to suggestions by some media outlets, diplomatic relations played absolutely no part in the decision not to publish the full report.”
The home secretary said: “This government is committed to stamping out extremism in all its forms and cutting off the funding that fuels it.
“The Commission for Counter-Extremism, which the prime minister announced earlier this year, will have a key role to play in this fight.
“We are determined to cut off all funding that fuels the evils of extremism and terrorism, and will work closely with international and domestic partners to tackle this threat.”