Matt O'Connor, founder of Fathers 4 Justice, said that ITV had conducted an undercover investigation using ex-security staff who were paid to infiltrate the organisation.
The men claim to have gathered filmed evidence of alleged members of Fathers 4 Justice engaged in acts of violence and intimidation, according to O'Connor.
"One member has been expelled on the basis of evidence supplied by ITV, and two others aren't even members," said O'Connor. "It's a big organisation with 12,000 members. We can't be responsible for the actions of people who aren't members."
O'Connor said he became suspicious that the organisation was being infiltrated some months ago and deliberately put out false stories to try and weed out those concerned.
Fathers 4 Justice asked to see all the evidence so that it can conduct a full investigation but claimed that ITV has refused.
ITV confirmed that it has made a programme on Fathers 4 Justice but declined to comment further.