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Businessman Donald Trump is fighting with Chicago Mayor Rahm Emanuel over a sign affixed to Mr Trump's downtown skyscraper.

The 20ft (6m) tall T-R-U-M-P sign was placed 200ft above the Chicago river and is backlit by bright lights.

Mr Emanuel's office said the mayor believed the "architecturally tasteful building" was "scarred" by the sign.

But Mr Trump has said the sign is "magnificent" and "popular" and argued the city previously signed off on it.

It enhances the building, he told NBC News, and said the building itself was "a great piece of architecture, great for Chicago".

"Cities love the brand and we are getting tweets, letters and phone calls from people who just love it ."

The real estate magnate and prolific tweeter blamed Blair Kamin, Chicago Tribune's architecture critic, for stirring up controversy with his harsh criticism during the sign's recent installation.

"If this sign was in Atlantic City or Las Vegas, nobody would care - but it is in Chicago, and in a part of Chicago full of great buildings from the 1920s to the 1960s and onward," Mr Kamin, a Pulitzer Prize-winner said.

None of the other towers have signs on them, he added, calling the Trump sign an "egotistical overstatement".

Mr Trump built the Trump International Hotel and Tower six years ago to replace an ageing Chicago Sun-Times building with its own sign. It is now the second-tallest building in the city.

The former tenants of the site agree with Mr Kamin.

"It is, rather, an obnoxious New York interloper, not unlike The Donald himself," wrote the Sun Times newspaper, which described the sign on its current building as "sociable but not loud".

Kelly Quinn, Mr Emanuel's spokeswoman, told the New York Times the mayor instructed Mr Trump's office to look into "options available for further changes".

But passers-by who were asked by NBC News on Friday to share their thoughts generally liked the sign.