Paris Hilton and Benji Madden have begun preparing to get married, according to reports.

The Good Charlotte guitarist was spotted donning a ring bearing the initials 'PH' over the weekend.

And during his band's performance at the Coachella Festival, his brother Joel introduced Paris as his "sister-in-law".

Speculations were aroused further when a group of people was spotted congratulating Paris in the VIP bar at the three-day event in Indio, California.

"Paris and Benji are inseparable - it's quite nauseating in some ways," the Mirror quoted an onlooker, as saying.

"A lot of people have brushed it off as a publicity stunt but Benji is serious about Paris and he has discussed marriage plans with his brother - which is why Joel called her his sister-in-law.

"He said it in a jokey way, but from the sound of things it's only a matter of time," the onlooker added.

Sources say Paris also took her sister Nicky along to the music bash to help bring her family closer to Madden.