In an interview this lunchtime with Andrew Neil on BBC Two's Daily Politics, Buscombe admitted that she was unaware of the scale of the scandal when she started at the PCC in 2009.
She also claimed that she had been "misled by the News of the World" before she agreed to clear the newspaper of the very same charge.
Two years ago, the PCC published a report dismissing allegations that it was misled by the News of the World during an inquiry into phone hacking. At the time, Buscombe said: "Having reviewed all the information available, we concluded that we were not materially misled."
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Pressed on the issue by Neil, Buscombe said today: "There's only so much we can do when people are lying to us. We know now that I was not being given the truth by the News of the World."
Buscombe also denied that she had sided with the newspaper, which is facing allegations that it used a private investigator to hack the phone of murdered schoolgirl Milly Dowler.
"My answer to this is the PCC takes all of this incredibly seriously," she said. "I'm seeing all the publishers and proprietors, I'm deeply unhappy with what happened."
Asked by Neil to name "one useful thing" the PCC has done over the phone hacking issue, Buscombe replied: "What I'm saying is we've beefed up our sanctions, we're making more demands, I've demanded to see all the proprietors."
Neil suggested that the newspaper industry should be subject to statutory regulation after the scandal, but Buscombe replied: "All I will say is that I think we have to be very careful about newspaper industry that's regulated by the state."
Rebekah Brooks, the chief executive of News of the World parent company News International, today promised the "strongest possible action" if the Dowler hacking allegations are proved true, but pressure is mounting on her to resign. Brooks, née Wade, was editor of News of the World at the time the alleged hacking was conducted by the Sunday tabloid.
The government has announced that there will be a three-hour debate in parliament tomorrow on the implications of the phone-hacking controversy.