The leader of a white supremacist group mentioned on a website attributed to Dylann Roof has been found to have given thousands of dollars to Republican politicians, including 2016 presidential candidates Ted Cruz, Rand Paul and Rick Santorum.

The Guardian reported that Earl Holt, who is president of the Missouri-based Council of Conservative Citizens (CofCC), had donated $65,000 to Republican campaigns in recent years based on reports from the Federal Election Commission.

Roof has been charged with the murders of nine people at the shooting at Emanuel AME Church in Charleston last Wednesday. At the weekend a manifesto was found on a website widely attributed to Roof that appeared to show an explanation for the attack, and cited information about "brutal black on white murders" he read about on the CofCC website. The Guardian also reported a number of racist comments posted online under Holt's name.

Upon learning about the connection, all three presidential hopefuls said that they would donate the funds to support the victims of the Charleston shooting.

Holt donated $8,500 to Texas senator Ted Cruz and his political action committee since 2012. A spokesman for Cruz told the Guardian: "Upon learning Mr Holt's background, Senator Cruz made an immediate decision to return his contributions.

"However after reflection, he decided that the best use of that money would not be to return it but instead use it to help support the families of victims from the Charleston shooting."

Holt also gave $1,750 to Rand Paul's political action committee. Paul's chief strategist Doug Stafford said the Kentucky senator "is donating the funds to the Mother Emanuel Hope Fund to assist the victims' families."

Similarly, Rick Santorum said he would also donate the $1,500 campaign contributions to the fund. "I abhor the sentiments Mr Holt has expressed," Santorum said.

Governor Scott Walker also said that he would also be giving the $3,500 he received to charity.

The FBI said on Saturday that they were investigating a website "allegedly attributed to Dylan Roof". The statement said they were also working to verify the authenticity of the photographs on the site, some of which show 21-year-old Roof posing with a gun and the Confederate flag.

According to Reuters the author of the website wrote: "We are told to accept what is happening to us because of ancestors wrong doing, but it is all based on historical lies, exaggerations and myths."

The author also said: "I have no choice... I chose Charleston because it is most historic city in my state, and at one time had the highest ratio of blacks to Whites in the country. ... Someone has to have the bravery to take it to the real world, and I guess that has to be me."

The CofCC has condemned the Charleston shooting and said in a post on their website that "We pray, for the sake of all Americans, that there will not be an escalation of racial tension."

However Holt said in a separate statement on Sunday that it was "not surprising" that Roof had cited information from the CofCC website. "The CofCC is one of perhaps three websites in the world that accurately and honestly report black-on-white violent crime," Holt said, adding that his organisation "is hardly responsible for the actions of this deranged individual merely because he gleaned accurate information from our website."

In the CofCC's statement of principles they say that they "oppose all efforts to mix the races of mankind".