Italian riot police used tear gas Saturday against thousands of people demonstrating against President Bush's visit to Rome.
Masked protesters threw bottles and other objects at police, disrupting an anti-globalization demonstration that was ending nearby.
Witnesses say one protester and at least one policeman were injured in the violence, while helicopters circled overhead.
The unrest broke out after a meeting between President Bush and Italian Prime Minister Romano Prodi, during which the two men discussed Lebanon, Iran and Serbia's breakaway Kosovo province.
Mr. Bush said Washington and Rome must make sure the the democratically-elected Lebanese government survives. As for Iran, Mr. Prodi said he and the U.S. leader agreed that Tehran must not be allowed to develop nuclear weapons. The two also said it is time to push ahead with independence for Kosovo.
Earlier Saturday, Mr. Bush met with Pope Benedict to discuss HIV/AIDS, conflicts in the Middle East, Latin America and Africa, with particular attention to Darfur. Mr. Bush said the pontiff expressed deep concern about the safety of the Christian minority in Iraq.
Mr. Bush also met with former Italian Prime Minister Silvio Berlusconi and a prominent Catholic lay organization, the Sant'Egidio Community.
President Bush travels on to Albania and Bulgaria before returning to Washington on Monday.