Britney Spears' has been targeted by online pranksters who have crudely mocked her private parts.

The 'Womanizer' singer was left red-faced when the upsetting message was posted on her account on networking site Twitter.

Hackers wrote: 'Hi Y'all! Brit Brit here, just wanted to update you all on the size of my vagina. It’s about four feet wide with razor sharp teeth.'

Site officials were quick to take down the offensive message, and insist they are working to make Twitter more secure.

A notice on the site read: 'A number of high-profile Twitter accounts were compromised this morning, and fake/spam updates were sent on their behalf.
We have identified the cause and blocked it. We are working to restore compromised accounts.'

Britney is not the only famous face to have her Twitter account hijacked.

Others to fall foul of jokers include US President-Elect Barack Obama, political commentator Bill O’Reilly and US newsreader Rick Sanchez.

Barack, who has not used the site since election day, apparently sent out an affiliate link to a survey asking what the US public really thought of him, with the promise of a prize of a gas card.

Bill’s site was changed to say the star was 'gay'.

Rick's page read: 'Rick Sanchez is high on crack and might not be coming in to work today.'