The U.S. government agreed to a police request to restrict more than 37 square miles of airspace surrounding Ferguson, Missouri, for purported safety reasons during 12 days of protests in August — but audio recordings obtained by The Associated Press show that local authorities privately acknowledged the purpose was to keep away news helicopters.

The new revelation is fresh evidence of the tension between law enforcement and media in the St. Louis suburb, where reporters and photographers said they suffered harassment by police while covering protests over the shooting of an unarmed black teenager by a white police officer this summer.

Examples include police firing tear gas at an Al Jazeera television crew, and officers arresting two reporters — Ryan J. Reilley of The Huffington Post and Michael Lowery of The Washington Post — as they sat charging their phones at a McDonald’s restaurant near the demonstration.

Authorities released the journalists hours later without charges, having swept them up for allegedly not leaving the restaurant fast enough after they were ordered to do so. Scott Olson, a Getty photographer, suffered a similar fate in police actions widely condemned by media organizations and press-freedom advocates. Police also told demonstrators, some of them citizen journalists, that they were not allowed to film officers, despite it being within their constitutional rights to do so.

But the AP’s exclusive report reveals a higher level of police attempts to hamstring media coverage of the demonstrations. On Aug. 12, the morning after the Federal Aviation Administration imposed the first flight restriction, FAA air traffic managers struggled to redefine the flight ban to let commercial flights operate at nearby Lambert-St. Louis International Airport and police helicopters fly through the area — but to bar others.

"They finally admitted it really was to keep the media out," said one FAA manager about the St. Louis County Police in a series of recorded telephone conversations. "But they were a little concerned of, obviously, anything else that could be going on."

At another point, a manager at the FAA's Kansas City center said police "did not care if you ran commercial traffic through this TFR (temporary flight restriction) all day long. They didn't want media in there."

FAA procedures for defining no-fly areas do not have an option to accommodate media restrictions.

"There is really ... no option for a TFR that says, you know, 'OK, everybody but the media is OK,'" the manager said.

FAA air traffic managers then worked out wording they felt would keep news helicopters out of the controlled zone but not impede other air traffic.

The conversations contradict claims by the St. Louis County Police Department, which responded to demonstrations following the shooting death of 18-year-old Michael Brown, that the restriction was solely for safety and had nothing to do with preventing media from witnessing the violence or the police response.

Police said at the time, and again as recently as late Friday to the AP, that they had requested the flight restriction in response to shots fired at a police helicopter.

But police officials confirmed there was no damage to their helicopter and were unable to provide an incident report on the shooting. On the tapes, an FAA manager described the helicopter shooting as unconfirmed "rumors."

The AP obtained the recordings under the U.S. Freedom of Information Act. They raise serious questions about whether police were trying to suppress aerial images of the demonstrations and the police response.

Such images would have offered an unvarnished view of one of the most serious episodes of civil violence in recent memory.

"Any evidence that a no-fly zone was put in place as a pretext to exclude the media from covering events in Ferguson is extraordinarily troubling and a blatant violation of the press's First Amendment rights," said Lee Rowland, an American Civil Liberties Union staff attorney specializing in First Amendment issues.

FAA Administrator Michael Huerta said in a statement Sunday his agency will always err on the side of safety.

"FAA cannot and will never exclusively ban media from covering an event of national significance, and media was never banned from covering the ongoing events in Ferguson in this case,” he said.

Huerta also said that, to the best of the FAA's knowledge, "no media outlets objected to any of the restrictions" during the time they were in effect.

Ferguson police were widely criticized for their response following the death of Brown, who was shot by a city police officer, Darren Wilson, on Aug. 9. In early October, a federal judge said the police violated demonstrators' and journalists' rights by forcing them to stay in constant motion.

"Here in the United States of America, police should not be bullying and arresting reporters who are just doing their jobs," President Barack Obama said Aug. 14, two days after police confided to federal officials the flight ban was secretly intended to keep media helicopters out of the area. "The local authorities, including police, have a responsibility to be transparent and open."

Al Jazeera and The Associated Press