Private investigator Glenn Mulcaire, one of two people already convicted over phone-hacking, has insisted he hacked phones "on the instructions of others".
A statement issued through his lawyers rebutted News International's claim that Mulcaire was acting on his own initiative.
"As an employee he acted on the instructions of others," his lawyers said.
"There were also occasions when he understood his instructions were from those who genuinely wished to assist in solving crimes.
"Any suggestion that he acted in such matters unilaterally is untrue. In the light of the ongoing police investigation, he cannot say any more."
Mulcaire said he had been "effectively employed" from 2002 until 2007 as a private investigator.
He apologised the day after it emerged that teenage murder victim Milly Dowler's phone had been hacked.
Now, a day after it was alleged that the mother of Sarah Payne had been given a phone by the News of the World which was subsequently hacked, he has apologised again.
"Glenn Mulcaire has already expressed his sincere regret to those who have been hurt and affected by his activities and he repeats that apology most sincerely," the statement read.
"As he accepted when he pleaded guilty in 2007 to charges of phone interception he admits that his role did include phone hacking."
News Corp only stopped paying Mulcaire's legal fees last week, after huge anger built up when it was revealed that he was still being assisted by the company.