Protester lands mini copter on US Capitol lawn

An anti-corruption protester was arrested after he landed his mini helicopter on the US Capitol lawn and piloted it through Washington's no-fly zone, triggering a national security investigation and shocking bystanders.

The Federal Aviation Administration said it is investigating the incident along with other US authorities, adding that the pilot was not in touch with air traffic controllers while in the air.

"The FAA did not authorize him to enter restricted airspace," the agency said in a statement.

The pilot, Douglas Hughes, was detained and illegal transport charges are pending against him, US Capitol Police said.

The arrested pilot is a Florida man who was conducting civil disobedience to call for campaign finance reform, according to the Tampa Bay Times, which had interviewed and filmed him prior to his audacious flight.

Air space is severely restricted around Washington landmarks, including the White House and the Capitol, which houses the US Congress whose 535 lawmakers were in session at the time.

A bomb squad inspected the gyrocopter, which landed a few hundred yards (meters) from the Capitol, but found nothing hazardous. It was cleared from the grounds hours later.

Authorities reportedly put the building on temporary lockdown, although it was not evacuated. Iraq's Prime Minister Haider al-Abadi was in the Capitol at the time for a meeting with senators.

Witness Rachel Jackman said she was alarmed after the incident.

"Within minutes, the entire area was shut down. I mean, there were probably 30 or 40 of the Capitol police there, cars, some black SUVs as well," she told CNN.

The breach during tourist season was the second air security scare this year in the US capital.

In January, an intelligence agency employee lost control of a hobby drone and crashed it on the White House lawn, prompting a Secret Service investigation.

President Barack Obama was briefed about Wednesday's incident, the White House said.

Air defense command NORAD told AFP that it only became aware of the incident after the gyrocopter landed.

NORAD spokesman Major Jamie Humphries said an investigation is underway to determine if the helicopter was detected by radar and why officials were not aware of the aircraft while it was in the air.

In addition to the FAA, the Secret Service and a handful of other US agencies are investigating the landing.

- 'Patriot,' not bomber -

"I'm demanding reform and declaring a voter's rebellion in a manner consistent with Jefferson's description of rights in the Declaration of Independence," Hughes, 61, reportedly wrote in letters to all 535 members of Congress and which he carried with him on his flight.

On the website Democracyclub.org, Hughes described what he wanted to achieve with his stunt.

"In every Congressional race in 2016, I want every candidate to take a stand on corruption," he apparently wrote.

Hughes is described as a mailman, and a logo appearing to be that of the US Postal Service was visible on the tail of the aircraft.

It appeared Hughes was flying a single-seat, open-cockpit Bensen-type gyrocopter, which the FAA classifies as an ultralight "vehicle" that requires no registration.

The gyrocopter typically cruises at 65 miles (105 kilometers) an hour, with flight times of no more than 90 minutes. No airport is required for takeoff and a rear propeller is used for thrust.

"They're designed very strictly for recreational, low-altitude flying," Dick Knapinski, spokesman for the Experimental Aircraft Association, told AFP.

A US Capitol Police officer told the Tampa Bay Times that Hughes "hasn't notified anybody" of his planned flight.

But his friend Mike Shanahan said he called a Secret Service agent to notify him of the flight hours before Hughes landed in Washington.

"He's not a suicide bomber, he's a patriot," Shanahan, 65, told the newspaper.