Washington, June 17 Actor Daniel Radcliffe found it hard to keep a straight face during the takes of the new Harry Potter franchise because Sir Michael Gambon was determined to make him laugh.

The 19-year-old star, who reprises his role in as the boy wizard in Harry Potter and the Half-Blood Prince, couldn't stop laughing in the company of 68-year-old Gambon, who plays his mentor Albus Dumbledore.

"All the scenes with Dumbledore were quite difficult, but they were great fun," Contactmusic quoted Radcliffe as saying.

"(Gambon) is wonderful and I love him and he's one of the greatest actors I've ever worked with, but it is amazing because he will be actively trying to make you laugh right up until the point the director says, 'Action'," he added. (ANI)