Jackson said he wanted to "cut his [Barack Obama's] nuts out" and he accused the fellow Chicagoan of "talking down to black folks" by giving moral lectures to black fathers to take better care of their children.

Fox was due to air the recording on Bill O'Reilly's show The Factor. But seeking to prevent a breech with the Democratic candidate Jackson has rushed out an apology.

"For any harm or hurt that this hot mic conversation may have caused, I apologize," Jackson said in a statement.

Jackson's own presidential aspirations went up in flames some years ago after he was reported making anti semitic remarks in what he thought was a private conversation with black journalists.

Now he says he cannot recall everything he'd said in the Fox News studio but says his offensive remarks were part of a discussion about Obama speaking to black churchgoers in which he has praises fatherhood and tells parents to turn off the TV and read books to their children. More recently he warned young students to stick with school and stop dreaming about becoming rap stars or professional basketball players.

Jackson says that by doing this Obama is hurting his relationship with black voters, "that the senator was cutting off his you-know-whats with the black people and black churches."

Jackson also told CNN that he had called the Obama campaign to apologize and indicate his support for the first black nominee with a chance of winning the White House.

"My support for Senator Obama's campaign is wide, deep and unequivocal," he said in his statement. "I cherish this redemptive and historical moment."

Obama had no comment.