The financial backers of a campaign group that had contact with the man later known as 'Jihadi John' are under pressure from British politicians and a regulator's investigation to explain why they gave it several hundred thousand pounds.

The Joseph Rowntree Charitable Trust, a Quaker foundation, and The Roddick Foundation, set up by the late founder of beauty retailer Body Shop, are among those now being asked how they came to fund Cage, a small activist group that called Mohammed Emwazi, who beheaded US, British and Syrian hostages, a once "beautiful young man".

"I condemn anybody who attempts to excuse that barbarism away in the way that has been done by Cage," British interior minister Theresa May told parliament in response to the comment by Cage's research boss Asim Qureshi to media last week.

Cage was set up by a group of London Muslims with the aim of supporting British suspects being held by the United States in Guantanamo Bay. Its activists blame US and British foreign policy for radicalising Muslims and accuse the security services of harassing those who refuse to be informants.

Britain's Charity Commission, a government-backed regulator, has launched an investigation into whether Cage's funders had ensured that their money was only used for purposes in line with their objectives. The Commission said in a statement on Monday that it had compliance cases open into the Joseph Rowntree Charitable Foundation and the Roddick Foundation.

"In both cases the commission's regulatory concerns revolve around how the trustees have ensured that charitable grants made to non-charitable bodies are only used for exclusively charitable purposes in line with their objects," it said.

The Joseph Rowntree Charitable Trust said in a statement that it had made three grants to Cage in 2007, 2008 and 2011, making a combined total of £305,000. It said its last grant payment to them was in January 2014.

The Roddick Foundation, set up to "support those who change the world", gave Cage £35,000 a year in the financial years ending in March 2012 and 2013, and £25,000 a year in the financial years ending in March 2010 and 2011, according to accounts made public by the Charity Commission.

The Joseph Rowntree Charitable Trust said it stood by its funding.

"We believe [Cage] has played an important role in highlighting the ongoing abuses at Guantanamo Bay and at many other sites around the world, including many instances of torture," it said in a statement.

The Roddick Foundation could not be reached for comment as its listed phone number was disconnected and emails to its public email address bounced back. Attempts to reach trustee Gordon Roddick via other organisations to which he is connected yielded no response.

SUPPORT

The relationship between Emwazi and Cage began in 2009, when he visited its drab office block in a back street behind the East London Mosque.

Cage held a news conference last week to publish emails sent to it from Emwazi over several years during which time he complained of being regularly harassed by security services.

On its Website, the group says: "Cage has been campaigning against the War on Terror for more than a decade."

Public information about Cage's finances is scant: It is listed in the UK companies register, but has filed accounts only for 2008 and as a small company it is not obliged to report each year.

According to Qureshi and its website, Cage is a non-profit making company limited by guarantee, a structure without share capital that is usually used to protect the people running the company from personal liability for its debts.

The group's other main funder, according to Qureshi, is the Network for Social Change, which describes itself as "a group of individuals providing funding for progressive social change". Its website says it comprises 110 donors from different backgrounds, including some "experienced philanthropists".

Reuters was unable to reach the group for comment, as its phone number is unlisted and it did not respond to emails asking for comment.

A British lawmaker told Reuters all of the charities that had funded Cage should dissociate from it after the group's comments at last week's news conference.

"It was both extraordinary and disgraceful, they were very clearly coming out as apologists for terrorism... Those that have provided them with support must very seriously question not only their support for Cage but how they got to make such a decision to support an organisation like this," said John Spellar, a spokesman on foreign affairs for the  Labour Party.

"I think there needs to be some very serious rethinking done by a number of these charities and NGOs about how they got into a position."

Cage's Qureshi said the group would continue its work regardless of the criticism levelled at it.

"Certain media organisations, right-wing think tanks, don't like our narrative as it goes against the prevailing national security paradigm," he told Reuters.

"Even though we aren't a proselytising organisation, we are a Muslim response to a problem that largely affects Muslims."

INVESTIGATIONS

British Prime Minister David Cameron's spokesman told reporters: "The prime minister thinks that it's absolutely right that the Charity Commission is undertaking the work that it is with regard to the funding of the organisation."

If the cases are escalated to inquiry level, and it is found that wrongdoing has occurred, the trustees of each charity can be suspended, an interim manager could be appointed to run the organisation or bank accounts could be frozen, said Sarah Hitchings, press officer at the Charity Commission.

She added that the investigation so far had found nothing to suggest that this would happen.

Cage's Qureshi said funding from such organisations paled in comparison with the money from individuals, though he said he did not have the figures available to share with Reuters.

"Every year in Ramadan we have a big fundraiser and people come, they pledge their support for the organisation and we collect the money from that, it helps keep us going," he said.

"The vast majority (of our money) comes from Muslim communities in the UK," Qureshi told Reuters. "They love our work. The community trusts us and believes in what we do."

The group's website invites donors to pledge money online, or arrange for someone to pick up a cash donation.

Rafik Aziz, who describes himself as the group's book keeper, said this arrangement was reached after British banks Barclays and the Cooperative closed the group's accounts last March in a move he said was triggered by the arrest of Moazzam Begg, Cage's Outreach Director, who both Britain and the United States have accused of terrorism offences.

Begg is the group's most high-profile figure, who spent nearly three years in the US Guantanamo Bay prison in Cuba after being seized in Pakistan in 2002. Last year he was charged with terrorism offences connected to Syria by British police but, after being held for seven months in custody and his trial about to start, the case against him was dropped.

Aziz said that since the bank account closures, the group had no success with other banks they approached, though he did not name the banks.

In addition to the Charity Commission investigation, Cage said last May that two of its board members were being investigated for fraud and tax evasion, although it did not name them and Reuters was unable to identify them.

A spokesman for HMRC (Her Majesty's Revenue and Customs) said that it was unable to confirm or deny any probe was happening due to rules about tax payer confidentiality.