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As District of Columbia police investigate NBC News' David Gregory for apparently holding up a restricted high-capacity magazine on his weekly Sunday show, the police department claims NBC was told in advance that the prop was "not permissible."

Gun laws in the nation's capital generally restrict the possession of high-capacity magazines, regardless of whether the device is attached to a firearm. Gregory, on "Meet the Press," held up what he described as one of those magazines during an interview with National Rifle Association CEO Wayne LaPierre.

That incident has since led to an investigation. And Metropolitan Police Department spokeswoman Gwendolyn Crump claimed Wednesday that NBC sought permission ahead of the show, and was denied.

"NBC contacted (the Metropolitan Police Department) inquiring if they could utilize a high capacity magazine for their segment. NBC was informed that possession of a high capacity magazine is not permissible and their request was denied. This matter is currently being investigated," Crump said in a written statement.

While interviewing LaPierre for Sunday's program, Gregory held an object, apparently as a prop to make a point, and said it was a magazine that could hold 30 rounds.

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"Here is a magazine for ammunition that carries 30 bullets. Now, isn't it possible if we got rid of these, if we replaced them and said, `Well, you can only have a magazine that carries five bullets or ten bullets,' isn't it just possible that we could reduce the carnage in a situation like Newtown?"' Gregory asked, referring to the December 14 mass shooting at an elementary school in Connecticut.

LaPierre replied: "I don't believe that's going to make one difference. There are so many different ways to evade that even if you had that" ban.

"Meet the Press" is generally taped in Washington.

An NBC News spokeswoman declined to comment Wednesday.

The Associated Press contributed to this report.