The fired "Today" show co-host says he's "embarrassed and ashamed" ... but also claimed that some of the allegations against him are "untrue or mischaracterized."

Lauer's ex co-workers, Savannah Guthrie and Hoda Kotb, read his statement at the top of the "Today" show Thursday morning -- and in it, he said his new full-time job was doing some "soul searching" in order to repair the damage.

He did not specify which of the myriad of allegations of sexual misconduct were untrue, in his eyes.

Meanwhile, Lauer's former cohorts soldiered on without him Wednesday night -- Al Roker, Hoda and Savannah looked tense during a break from taping the annual Rockefeller Center Tree Lighting special.