Cameron Diaz is reportedly fed up with boyfriend Justin Timberlake calling up ex-flame Britney Spears.

"Justin says he's being supportive, but Cameron has told him to cool it," Sky News quoted a friend of the couple as saying.

The former 'N Sync singer split from pop diva Spears in 2002 after spending three years together.

Timberlake officially proposed to the "My Best Friend's Wedding" star Diaz over Christmas.