Pope becomes one of world's oldest YouTube stars

Archbishop Claudio Celli, head of Vatican communications said the Vatican could not exclude that someday it would have its own space on Facebook, the social networking site.

In his welcome message to users of YouTube, the pope said he hoped the initiative would be put to "the service of the truth."

In his separate, written message for the Church's communications, he cautioned young people to seek quality and not quantity in their on-line relationships and not to forget human contact.

"It would be sad if our desire to sustain and develop on-line friendships were to be at the cost of our availability to engage with our families, our neighbors and those we meet in the daily reality of our places of work, education and recreation," the pope wrote.

"If the desire for virtual connectedness becomes obsessive, it may in fact function to isolate individuals from real social interaction while also disrupting the patterns of rest, silence and reflection that are necessary for healthy human development," he said.

The pope also said it would be "a tragedy for the future of humanity" if a so-called digital divide were allowed to widen to the point where it excluded disadvantaged areas of the world that are already economically and socially marginalised.

(Editing by Matthew Jones)