Anthony Weiner, a Democratic congressman, has claimed his Twitter account was hacked after a photograph of a bulging pair of underpants was sent to a follower. Here are some of the most memorable social networking 'hacks':

1. Axi Rose

In August last year, the Twitter account of the Guns 'N' Roses singer was hacked by an itnruder who pretended all the dates of the band's European tour were cancelled.

The tweet stated: "All upcoming Guns N' Roses dates are officially canceled. Please contact your place of purchase for any refunds."

However, it was quickly claimed to be a hoax because the singer rarely posts messages on his account and the announcement was the first for almost 100 days. Rose has repeatedly pulled out of concerts in the past.

 2. Nicolas Sarkozy

Hackers broke into the Facebook page of the French president to announce he would be quitting next year. The message was seen by about 350,000 'friends' of Mr Sarkozy, with the post soon creating buzz on the web. The message suggested meeting outside the same Paris restaurant on May 6, 2012, where he celebrated his election, to celebrate his resignation. Mr Sarkozy's team apologised for the security lapse.

 3. Mark  

, Mark Zuckerberg, the Facebook founder, was targeted by hackers, who took over his Facebook page and wrote: “Let the hacking begin: If Facebook needs money, instead of going to the banks, why doesn't Facebook let its users invest in Facebook in a social way? Why not transform Facebook into a ‘social business’ the way Nobel Price winner Muhammad Yunus described it? http://bit.ly/fs6rT3 What do you think? #hackercup2011“

4. North Korea

 The government's official Twitter account in January called for an uprising to remove the leaders from power. The feed ranted about huge spending on nuclear weapons and Kim Jong-il's drinking parties, "while 3 million people are starving and freezing to death." The country's official YouTube site was also seemingly hacked.

5. Barakas Obama

In March last year, a 25-year-old unemployed Frenchman was arrested for hacking the Twitter accounts of Barack Obama and Britney Spears. Investigators said he used common sense rather than any significant hacking, by guessing the passwords of a lot of users. He also allegedly targeted Lily Allen and Ashton Kutcher.