Rising star Nick Flanagan is reportedly under investigation from the Australian Golf Union over possible breaches of his amateur status.

The Australian newspaper said the AGU's investigation over scholarship funds could cost Flanagan the historic 2003 US Amateur golf title the 19-year-old sensationally won on Monday.

The Newcastle teenager followed the likes of his idol Tiger Woods, Arnold Palmer and Jack Nicklaus when he claimed the US Amateur title in a sudden death play-off over American Casey Wittenberg at Pennsylvania.

He was the first Australian to win the tournament in 100 years.

The Australian report said AGU chief executive Colin Phillips would investigate claims that Flanagan's expenses had been paid by a scholarship from the Jack Newton Junior Golf Foundation.

It also said Phillips would examine claims that Flanagan used scholarship money to fly to the US.

The report said Flanagan returned to Australia on Wednesday and would meet with Phillips "in the next few days".

"This is pretty embarrassing for him and us and if the USBA get on to it, it could cause big problems," Phillips told The Australian.

Brought to you by AAP © 2024 AAP