The man identified himself on the banner as Julian Jungarean, a
Romanian who has previously scaled the colonnade around the piazza.
Witnesses say uniformed officers were speaking with him from the ground
and a nearby roof.
Benedict celebrated New Year's Day Mass earlier Tuesday in St. Peter's
Basilica and said he was convinced that peace will prevail in 2013
despite the inequality, terrorism and "unregulated financial capitalism"
that afflict the world today.
He later appeared at his studio window overlooking the piazza to wish thousands of people below a Happy New Year.
Jungarean's protest didn't appear to cause the pope any disturbance.