The campaign for presidential candidate Herman Cain has said that it will investigate potentially illegal campaign donations from a charity founded by the candidate's chief of staff, Mark Block.

"We are doing a full investigation of it and if there were any improprieties we will go back and amend the FEC reports," Cain said Tuesday on "The Laura Ingraham Show." "The last I want to do, Laura, is to do anything illegal or something that we shouldn't do. So at this point we are going back through and double checking and making sure that we have all the i's dotted and all the t's crossed."

According to the Milwaukee Journal Sentinel, the tax-exempt nonprofit Prosperity USA was owed about $40,000 by the campaign for expenses that included iPads, chartered flights and travel to early-primary states. The organization was run by Block and Lisa Hansen, Cain's current deputy chief of staff.

The group also paid as much as $100,000 to a conservative black organization before Cain spoke at the group's Martin Luther King Jr. Day dinner in January.

Those donations are not allowed under election law, and the campaign said it would hire a lawyer to investigate whether it possibly broke the law. It is not clear whether the campaign has fully paid back these amounts, but the nonprofit now appears to be defunct.

"As with any suggestions of this type, we have asked outside counsel to investigate the Milwaukee Journal Sentinel’s suggestions and may comment, if appropriate, when that review is completed," Block said in a statement.

The Federal Election Commission said Tuesday it would not begin an investigation into the donations until a formal complaint was filed. 

This post was updated at 12:32 p.m.