Katy Perry took her grandma to the premiere of 'Smurfs 2'.

The popstar walked the special blue carpet alongside her 92-year-old grandmother Ann Hudson at the Los Angeles premiere of the new animated movie at the Regency Village Theatre in Westwood, California, on Sunday (28.07.13).

Ann - who wore a T-shirt printed with the phrase, ''I've got the hots for Papa Smurf' - also sported a special jewel-encrusted walking stick.

Katy voices Smurfette in the movie and joked she had helped her demanding grandma with her outfit for the special occasion.

The 28-year-old singer laughed: ''Grandma and I, it's always been a love-hate relationship. Just always at [each others'] neck.''

The 'Smurfs 2' follows celebrity sorcerer, Gargamel, who creates smurf-like creatures called The Naughties in a bid to collect a ''magical Smurf essence''.

He kidnaps Smurfette whilst the other Smurfs seek their friends Patrick and Grace Winslow and their son, Blue to help rescue Smurfette.

Other stars in attendance at the premiere included Britney Spears, Neil Patrick Harris and David Burtka.

Katy also revealed she secretly collaborated with Britney on the song 'Ooh La La', which appears in the film.

Speaking to E! News, Katy said: ''Me and Bonnie [McKee] secretly did some background vocals on that song. So maybe listen for our voices.''