Lady Gaga accuses Perez Hilton of stalking: Do celebrity critics tend to cross the line?

Lady Gagas wax likeness figure is unveiled by television personality Perez Hilton at Madame Tussauds in Hollywood, California on December 9, 2010. (Getty Images)

They used to be friends. He called her his 'wifey'. And now she's calling him a stalker.

Lady Gaga and Perez Hilton are currently in the middle of a Twitter spat of almighty measures.

It seems the trouble started when Hilton praised Katy Perry's single Roar, over Lady Gaga's single Applause - both of which were battling for the top spot in the US.

He retweeted several tweets from people commenting on the lacklustre sales of Gaga's new single, such as:

On discovering Hilton had viewed an apartment in her building, Gaga is reported to have said:

"STAY AWAY FROM ME + MY FAMILY YOU ARE SICK TRYING TO RENT AN APARTMENT IN MY BUILDING TO STALK ME. LEAVE ME ALONE!!!" But the tweet was later removed.

Hilton is now retweeting abuse and death threats he is receiving from Gaga's 'Little Monsters', and said:
"I can't sleep. I am literally sick to my stomach. Not playing any f***ing games here. I am afraid for my f***ing safety and that of my son."

In his official statement, Hilton said he was a critic, not a stalker.