Jaden Smith has denied launching a foul-mouthed rant at a female fan online.

A message appeared on an Instagram account believed to belong to the 14-year-old 'The Karate Kid' actor, who is the son of Will and Jada Pinkett-Smith, featuring a string of obscene language.

The message read: ''B***h a** n***a lil a** girls stop hiding Android stank p***y a** lil girl the whole sea live in yo p***y wanna be MSFTS can't afford to get ya hair did but you f**king with my fans get ha get your life together (sic).''

The comment, which was posted by what is believed to be the young star's handle @letsmakeitdotorg, came in response to a fan who said: ''Let me shut Up Yo'' after the account holder initially stepped in when she called another fan fat in a heated debate.

Jaden quickly took to his official Twitter account to deny the rant was posted by him.

He wrote: ''I Would Never Say Anything Like That To Anyone Let Alone A Women I Stand For My Republic Msfts Over All.''

A spokesperson for the actor also told gossip website GossipCop.com: 'This was 100% not him.''

Some of the actor's fans believe the message was posted from a parody of Jaden's Instagram account, which uses a lower-case L in place of the I in the handle.