Access to the official website of Madrid World Youth Day 2011 was blocked on Thursday in a presumed attack by hackers a few hours after Pope Benedict XVI arrived in Madrid for the Catholic Church's World Youth Day, a weeklong Catholic festival that is taking place against a backdrop of the European debt crisis and social unrest among the young that exploded recently in the riots in Britain.

A statement on the TV screens of the press center of the WYD11 warned the official website of Madrid WYD11 was "experiencing technical problems due to hacking".

"We are trying to resolve these problems. We appreciate your cooperation and apologize for the inconveniences caused by sources unrelated to the organization", the statement added.