The producer, who was not identified by the sources, is Miami-based. NBC News declined to comment when asked about the dismissal, which the sources said took place on Thursday.

Reuters had previously reported that the "seasoned" producer was at the center of the probe.

NBC News executives interviewed more than half a dozen employees during their investigation of the network's editing of the tape of the 911 call placed by George Zimmerman before he shot the unarmed Florida teenager, sources at the network had said on Thursday.

The edit made it appear as though Zimmerman told police that Martin was black without being prompted, when, in fact, the full tape reveals that the neighborhood watch captain only did so when responding to a question asked by the dispatcher.

The clip aired on the network's flagship "Today" morning show last week.

Public pressure has been building on the network to fully explain the incident - which critics charge has inflamed racial tensions in an already volatile situation.

On Thursday, a New York Post editorial characterized the edited 911 call as "pretty damning evidence of willful misconduct by NBC News" and suggested that racial violence could ensue over irresponsible news coverage.

Sources at the network said on Thursday that NBC News executives did not know the 911 call was misleadingly edited until news reports surfaced days later on right-leaning blogs includingNewsbusters.org and Breitbart.com.

NBC News has apologized for the incident.

The Today show's editorial control policies - which include a script editor, senior producer oversight, and in most cases legal and standards department reviews of material to be broadcast - missed the selective editing of the call, said an NBC executive.

The network's executives have vowed to take rigorous steps to formalize editorial safeguards in the news division following the incident, one source at NBC said on Thursday.

News of the firing - which was reported by The New York Times late on Friday - surprised and dismayed some NBC News employees involved in the network's ongoing coverage of the case, according to two sources, who said the producer was highly regarded within the organization.

NBC is owned by NBC Universal, a unit of Comcast Corp .

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