The German city of Hamburg is bracing for a mass
drunken party organised via Facebook on its metro system in
September, a day before an alcohol ban on trains starts,
authorities said Thursday.

They fear that the September 30 event may be similar to when
revellers caused mayhem on London's transport system on May 31,
2008 before drinking on tubes and buses in the British capital
became illegal.
According the Bild daily, more than 19,000 people in the lively
German port city have already indicated on Facebook they they
planned to attend, although a link on the social networking website
was no longer visible on Thursday.
A spokesman for the northern city's transport operator,
Hamburger Hochbahn, said the company was currently "in talks" with
the relevant authorities and was following the situation
closely.
A number of "Facebook parties", when a get-together announced on
the website is gatecrashed by large numbers of unwanted guests,
have alarmed police and hit the headlines in Germany in recent
weeks.
In early June some 1,500 unwanted guests tried to attend a
girl's 16th birthday party in Hamburg that she had announced on
Facebook. The teenager forgot to mark the invitation private and
even included her parents' address.
Last Friday the western city of Wuppertal saw clashes between
police and youths setting off fireworks and throwing beer bottles
after 800 people turned up at a party called by an anonymous
Facebook user.
Police used pepper spray and took 41 people into custody, while
16 others were injured. Including a major clean-up the next day,
the party cost taxpayers around 120,000 euros ($170,000), reports
said.
Authorities in Wuppertal have attempted to ban another party
organised by a 16-year-old due to take place on July 1 that 1,600
people have said on Facebook they planned to come to.