Former Beatle Paul McCartney performed a flash concert in New York's Times Square Thursday, sparking a Twitter frenzy by announcing the free gig at an hour's notice.

"Wow! Really excited to be playing New York Times Square at 1pm this afternoon!" he wrote to his 1.6 million followers in a message retweeted more than 540 times.

Coinciding with lunchtime for thousands of busy New Yorkers, McCartney's impromptu set included four tracks from his latest album "New," which comes out next week.

Excited fans flooded Twitter with cell phone pictures and jerky video clips taken from the crowd of McCartney and his band performing from inside the rear of an open semi truck.

Less than two hours later, there was no sign of the concert performed on 46th and Broadway, where tourists thronged the streets oblivious to what they had missed.

It was the latest in a series of seemingly spur of the moment promotional events for "New," which debuts in Britain on October 14 and in the US on October 15.

On Wednesday, McCartney performed at the Frank Sinatra School of the Arts in Queens, playing 13 songs and answering questions from students.

He dedicated the title track from "New" to his third wife Nancy, telling the delighted teenage audience that Wednesday was also their second wedding anniversary.

The concert took place on what would have been the late Beatle John Lennon's birthday and McCartney paid tribute by performing "Being for the Benefit of Mr. Kite!"