Paris Hilton has revealed the reason for the rift that tore apart her friendship with Nicole Richie, days after vowing to keep silent about it.

"A good friend is someone who is honest... I'll test them by telling them something and seeing if it will get out. If it gets out, I know that it was them," the Internet Media Database quoted the hotel heiress as saying.

The two rich women broke up their comradeship after they teamed up on reality TV show "The Simple Life". Paris has now backtracked on her pledge to keep their fight private, ending months of speculation.