A Mexican student was arrested in Madrid on Tuesday after posting his intention to attack anti-papal protestors with toxic gases, including sarin, on the internet.
A staunch Catholic, the man said that he could not allow protests against the pope. Benedict XVI is due to arrive in Madrid on Thursday ahead of a weekend of events to mark World Youth Day 2011. Hundreds of thousands of Catholic faithful have already descended on the capital. The pontiff is scheduled to attend a welcome ceremony in the downtown Cibeles area on Thursday evening and to hold a Mass at the Cuatro Vientos aerodrome on Saturday night.
World Youth Day 2011 officially began on Tuesday, with a Mass in Cibeles presided over by the archbishop of Madrid, José Antonio María Rouco Varela. World Youth Day runs until Sunday August 21.
Since Tuesday, many of the city's main roads have been closed off due to the papal visit.