Opposition parties have condemned the government for opting not to publish a much-delayed report into the funding and support of extremist groups, saying the decision appeared intended to bury any criticism of Saudi Arabia.

But the home secretary, Amber Rudd, said the move was based on national security and claimed that the full report contained sensitive and detailed personal information.

Announcing the decision in a written parliamentary statement, Rudd instead published a 430-word summary of the report, including that some extreme Islamist groups receive hundreds of thousands of pounds a year in funding, mainly from UK-based individual donors.

The summary said the most common source of support for extremist organisations was from small, anonymous public donations, mainly from individuals in the UK.

It also said overseas backing helped some individuals study at institutions “that teach deeply conservative forms of Islam and provide highly socially conservative literature and preachers to the UK’s Islamic institutions”, adding: “Some of these individuals have since become of extremist concern.”



However, the summary did not name the countries of origin for such funding or mention Saudi Arabia or any other nations.

Rudd said the full report, commissioned by David Cameron, was being withheld “because of the volume of personal information it contains and for national security reasons”. Opposition MPs who were members of the privy council would be able to view the full report at the Home Office if they did not divulge the contents publicly, she added.

But Diane Abbott, the shadow home secretary, said this did not go far enough, and the public “has a right to know if any governments, foreign or domestic organisations or individuals are funding extremism in this country”.

“Of course, security intelligence should not be compromised but this is easily achieved by redaction and other means. The government would never have commissioned this report if it considered this problem insurmountable.

“Instead, 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.”



Caroline Lucas, the Green co-leader, who has campaigned for the report to be published, said the refusal to do so and the “utterly vague statement” in its place was unacceptable.



She added: “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 Liberal Democrat leader, Tim Farron, said the decision to not publish the report was “utterly shameful”.

He said: “Instead of supporting the perpetrators of these vile ideologies, the government should be naming and shaming them – including so-called allies like Saudi Arabia and Qatar if need be.”

Theresa May’s spokesman said the prime minister supported Rudd’s reasons for not publishing the full report. Asked whether this did mention Saudi Arabia, he said: “All the information that has been put in the public domain is there in the written statement, and I’m not in a position where I can add to that.”

The summary found that while small individual donations were the most common funding source, and in some cases extremist organisations received hundreds of thousands of pounds a year. It added: “This is the main source of their income. Those giving may not know or support the organisations’ full agenda.”

Some extremist Islamist organisations “portray themselves as charities to increase their credibility and to take advantage of Islam’s emphasis on charity”, and are vague about both their activities and their charitable status, it said.

The statement 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.”



The inquiry was begun as part of a deal with the Liberal Democrats during the coalition government, in exchange for the party supporting the extension of British airstrikes against Islamic State into Syria in December 2015.



The summary said that tackling the problem of extremist funding would need a range of measures, notably connected to domestic sources of support.



In response, Rudd’s statement said the government would seek to raise awareness “to encourage people to understand the full aims of the organisations that they give to”, and alert the financial services industry about extremism concerns.

It added: “These organisations have an interest in ensuring they are not inadvertently supporting extremist individuals or organisations.” Also, the statement said, the Charity Commission would introduce a requirement on charities to declare overseas funding sources.

The government would also be “directly raising issues of concern, supported by evidence, with specific countries as part of our wider international engagement on countering extremism and violent extremism”, it added.