A 24-year-old man is set to become $US1 million richer for streaking in front of President Barack Obama during a rally in Philadelphia.

Billionaire shipping tycoon Alki David offered to pay the sum to the first person who ran nude in front of Mr Obama with the word “BATTLECAM” - the name of his website - across his chest.

Juan James Rodriguez will receive the money in cash once Mr David sees the video and confirms that all conditions for the stunt were met.

In order to win the money, Mr Rodriguez had to be naked, be within eyeshot and earshot of Mr Obama, and yell the words “Battlecam.com” six times.

But that was not the only attention-getting stunt at the rally. Shortly after Mr Obama's speech ended, a man threw a paperback book toward the president and was immediately detained by Secret Service agents, AFP reported.

He was later released without charge after an investigation found that he had meant no threat to Obama, Secret Service spokesman Edwin Donovan said.

The man, who was not identified, was described by Mr Donovan as an "over exuberant" supporter who wanted the president to read a copy of a book he had written.

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Originally published as $1million prize for Obama streaker