By Chris Francescani

NEW YORK, April 7 (Reuters) - NBC News' decision to air an edited call from George Zimmerman to police in the moments before he shot Trayvon Martin was "a mistake and not a deliberate act to misrepresent the phone call," according the president of network's news division.

The edit in question, which aired on the network's flagship "Today" morning show last week, made it appear that 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 posed by a dispatcher.

Under growing public pressure to explain the incident, NBC News President Steve Capus provided Reuters with the fullest explanation to date of how the edited call made it on air and what the network is doing to prevent such a consequential error from happening again.

Capus confirmed a previous Reuters report that an internal network investigation had determined that a producer made the editing error, and that the network's editorial controls - including senior broadcast producer oversight, script editors and often legal and standards department reviews of sensitive material to be broadcast - simply missed the selective editing of the phone call.

He said the producer has been fired and "several people" involved were disciplined, though he declined to specify the nature of the disciplinary actions, saying they were internal personnel matters.

Sources at the network told Reuters on Thursday that NBC News executives did not know the emergency call was misleadingly edited until news reports surfaced days later on blogs including newsbusters.org and Breitbart.com.

Those blogs, along with media critics and rival networks, have charged that the edited call has inflamed racial tensions in an already volatile situation.

Sources inside the network have told Reuters that NBC News brass interviewed more than a dozen staffers during its investigation of the matter.

As part of the investigation, the producer who edited the call was questioned extensively about motivation, and it was determined that the person had cut the video clip down to meet a maximum time requirement for the length of the segment - a common pressure in morning television - and inadvertently edited the call in a way that proved misleading.

NBC News has apologized for the incident, saying in a statement to Reuters earlier this week that there was "an editing error in the production process," but insisting the results of the internal investigation would not be announced publicly.

Capus said that the network "takes its responsibility seriously" and has undertaken rigorous efforts to formalize the editorial safeguards in place at the network.

He said that NBC News' broadcast standards department, led by David McCormick, has been holding meetings with various NBC News shows, as well as the network's specialized units, which handle sometimes complicated subjects like medical or legal news. Capus added that he also is holding meetings among the network executives to reinforce the lessons learned from the investigation into the edited call.

SHARPTON CONTROVERSY

Capus has also worked in recent days to quell both external and internal criticism over the network's coverage of the highly charged news story - most of it focused on the central role that civil rights activist and MSNBC talk show host Reverend Al Sharpton has played in the case.

Sharpton, who hosts MSNBC's "Politics Daily" and offers regular commentary on the case, has also served as an advocate for the Martin family by leading rallies demanding Zimmerman's arrest, appearing beside Martin's anguished parents, and conducting closed door meetings with prosecutors and local officials on the Martin family's behalf. A call to Sharpton for comment Saturday was not returned.

Externally, media critics including Howard Kurtz, host of CNN's "Reliable Sources" and a columnist for The Daily Beast, have criticized the network for allowing Sharpton to play a dual role as both activist and commentator.

"Even commentators have to abide by certain rules," Kurtz wrote last month. "And in this case, by playing both sides of the camera, Rev. Al has obliterated them."

Internally, some NBC news staffers have complained that Sharpton's unique role in the case has compounded the damage to NBC News' reputation that the edited tape caused, and contributed to an impression among its critics that the network as a whole is biased against Zimmerman, according to sources.

Capus refuted that claim.

"Reverend Sharpton is a talk show host on MSNBC," Capus said. "We believe there's a distinction between the role he plays and our front line journalists who are part of NBC's news gathering and reporting. This is a large news organization that has many people involved in any number of different aspects of coverage and commentary. That's the distinction we've made as a news organization."

MSNBC chief executive Phil Griffin has defended Sharpton's dual role as well, saying that as long as the longtime civil rights activist is upfront about his advocacy activity, he would be allowed on a "case by case basis" to both participate in and comment for MSNBC on issues and stories that interest him. Griffin has credited Sharpton with turning the Martin case into a national news story.

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

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