Katie Couric has opened up for the first time following Matt Lauer’s abrupt firing from NBC and claimed she had “no idea” about the disgraced “Today” show co-host’s inappropriate behavior when she worked with him.

Couric, 61, told People that learning about Lauer’s lewd behavior was “painful” for her.

“The whole thing has been very painful for me,” Couric told People. “The accounts I’ve read and heard have been disturbing, distressing and disorienting and it’s completely unacceptable that any woman at the ‘Today’ show experienced this kind of treatment.”

Couric and Lauer hosted the “Today” show together from 1991 to 2006 before she left to anchor “CBS Evening News.”

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“I had no idea this was going on during my tenure or after I left,” she said. “I think I speak for many of my former colleagues when I say this was not the Matt we knew. Matt was a kind and generous colleague who treated me with respect. In fact, a joke I once made on late-night television was just that, because it was completely contrary to our brother-sister relationship. It’s still very upsetting. I really admire the way Savannah [Guthrie] and Hoda [Kotb] and the entire ‘Today’ show staff have handled a very difficult situation.”

The joke Couric was referring to came when she appeared on Andy Cohen’s “Watch What Happens Live” in 2012 and was asked what Lauer’s most annoying habit was.

“He pinches me on the ass a lot,” Couric responded. The video resurfaced and circulated on the internet following the news of Lauer’s firing.

Guthrie and Kotb announced during the “Today” show on Nov. 29 that Lauer was fired after the network received “a detailed complaint from a colleague about inappropriate sexual behavior in the workplace” by the former host.

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Following Lauer’s termination, a number of reports and accounts from former employees were revealed. Variety published an expose on Lauer following his firing. The expose claimed Lauer had a button under his desk that allowed him to lock his door from inside without getting up. One woman claimed Lauer sexually assaulted her in his office until she passed out.

Couric briefly spoke out after Lauer’s firing on Instagram in December when she told a social media user that she would “say something when I’m ready to.”

Lauer has laid low following his termination. Former colleague Willie Geist told “Entertainment Tonight” this week that Lauer was “as good as he can be.”

NBC’s parent company Comcast is conducting an investigation to determine who knew about Lauer’s sexual misconduct and when they learned of it. Fox News has learned that the investigation is now being conducted outside of NBC News chairman Andy Lack’s division.

Fox News’ Brian Flood contributed to this report.