Barbara Walters has apologised to Katy Perry for upsetting her almost two years ago.

The 'Roar' hitmaker, 28, claimed in a recent interview that the veteran US broadcaster gave her a tough time in late 2011 when her marriage to comedian Russell Brand was falling apart, but 'The View' co-host insists she had no idea Katy was so unhappy at the time.

The 84-year-old journalist said: ''Katy, if I made you feel at all unhappy, during a time when you were obviously unhappy, and I didn't know, I'm sorry. But you can't always know!''

Katy admitted last week that she regretted sitting down for a chat with Barbara for the presenter's 'Top 10 Most Fascinating People of 2011' in December of that year because her marriage was in tatters at the time and she was forced to pretend it had been ''lovely, so far''.

She said: ''I shouldn't have done the interview: I was playing Madison Square Garden that same night, and I knew that the end of my marriage was coming. I was just exhausted and stressed.''

She also told Billboard magazine: ''I'd prepped everyone that I was running late, but Barbara showed up at the original time anyway. When I got there, I apologised immediately, but then she said to me, 'You know, I've only ever waited for one other person this long, and you know who that person was? Judy Garland. You know how she turned out, right?' I was like, 'Oh, snap! Yes, b***h!'''

But Katy, who announced her split from Russell on December 30, 2011 after 14 months of marriage, also hinted that she wasn't holding a grudge against Barbara.

She added: ''I think it's the coolest thing that Barbara Walters shaded me. I just couldn't tell her as we were sitting down for a mega-interview, 'Hey, my marriage is falling apart. Give me a break.'''