A 75-year-old aviation enthusiast whose plane strayed into restricted airspace during a presidential visit, prompting fighter jets to be scrambled, has brushed off the incident.

Two F-16s intercepted Myrtle Rose's aircraft as she took to the skies over the suburbs of Chicago city on Wednesday afternoon.

The widow told US media she thought the warplanes were just admiring her plane.

The agency which oversees air safety in America said it was investigating.

When F-16s come screaming up to you, they are probably trying to tell you something Stacey Knott , North American Aerospace Defense Command

Because of President Barack Obama's visit to Chicago on Wednesday to attend a fundraiser marking his 50th birthday, restrictions were in place forbidding private pilots to come within 30 miles (48km) of the city's O'Hare Airport.

'Just looking'

Ms Rose told the Associated Press news agency that before flying her Piper J-3 Cub aircraft she normally checks for any airspace restrictions on her computer, but it was not working properly that day.

"I hadn't flown in over a week," Ms Rose told AP. "It was a beautiful afternoon."

She also said she did not have her radio on. Jets were scrambled from Toledo, Ohio, when air traffic controllers were unable to contact her.

Asked what she thought when the F-16s appeared, Ms Rose told AP: "I thought, 'Oh, well, they're just looking at how cute the Cub is.'"

When Ms Rose landed on an airstrip on the outskirts of Chicago, police were waiting.

The North American Aerospace Defense Command (Norad), which scrambled the two warplanes, said there was no excuse for not knowing about the airspace restrictions.

"The biggest thing to keep in mind is that when F-16s come screaming up to you, they are probably trying to tell you something," said Norad spokeswoman Stacey Knott.

Ms Rose said she had filled in a report with the Federal Aviation Administration, which said she could face a fine, a pilot's licence suspension, or no action at all.