Justin Bieber has threatened to sue house guests for $5 million if they talk about his parties.

Friends invited to party at the 'Boyfriend' hitmaker's mansion in Calabasas, California, face being sued if they discuss the events of his bashes in public or on Twitter.

Party guests are required to sign a confidentiality agreement upon entering the house, promising not to reveal details of Justin's ''physical health, or the philosophical, spiritual or other views or characteristics'', according to documents obtained by TMZ.

This includes a ban on tweeting, blogging or other forms of social media.

The document went on to warn Justin's pals that his parties were ''potentially hazardous and you should not participate unless you are medically able and properly trained''.

The revelation comes after a close friend posted a photo of the singer appearing to smoke marijuana on Instagram and it seems the pop star is struggling to get over the abuse of trust, isolating himself from pals as a result.

He confessed to Teen Vogue last month: ''Now I just don't trust anybody. Literally, my phone never rings.

''I only have, like, four people that I keep in contact with. I don't need a bunch of friends to make me happy.

''I just need the people close to me that I love, that's all.''