Lady Gaga has used her keynote speech at the SXSW music festival to tear a strip off the media.

According to Digital Spy, the 27-year-old star condemned writers for comparing the sales performance of her ARTPOP album to Katy Perry's Prism.

"I don't know what the f**k all I have to do with Katy Perry," she declared. "My music is completely different.

"We've sold over 2.5 million copies of ARTPOP all over the world. I'm sorry I didn't sell a million records the first week, but I have before!"

And she went on: "I'm very proud of what we did, we sold as much as everybody else. When it comes to me, everybody forgets where the music business is now."

Gaga also teased fans by revealing that she had a whole extra album worth of material - but that she's keeping it for herself and her homies.

"I have a whole second act of ARTPOP," she continued. "There are many volumes of work over a long period of time that've just not been released to the public.

"I've chosen not to put into the system... because sometimes it's just fun to have records that me and my friends listen to."

"We love them and we don't care what anybody else thinks... maybe one day I'll release them."

Gaga has been targeted by an angry Demi Lovato over a vomiting performance artist in her SXSW show.