Tens of thousands of anti-war protesters have taken to the streets in Rome as US President George W Bush visits the Italian capital.
Flare-throwing protesters are among the anti-war marchers
Crowds of demonstrators shouting "No Bush, no war" marched through the city.
The protest came hours after Pope John Paul II reiterated his condemnation of the US-led war in Iraq in a meeting with Mr Bush at the Vatican.
Riot police fired some tear gas in the tense but mostly peaceful rallies, in which flares and fireworks were thrown.
Organisers say 150,000 people have turned out for the protest, while police put the figure at 25,000.
In his meeting at the Vatican, Mr Bush presented the Pope with the American Medal of Freedom, calling him a "son of Poland who became the Bishop of Rome and a hero of our time".
The Pope, who has Parkinson's Disease, struggled to speak clearly as he addressed the US president.
He reiterated the Vatican's opposition to the war in Iraq and said everyone wanted the situation to be normalised as quickly as possible "with the active participation of the international community and in particular the United Nations".
He added: "In the past few weeks other deplorable events have come to light which have troubled the civic and religious conscience of all, and made more difficult a serene and resolute commitment to shared human values: in the absence of such a commitment neither war nor terrorism will ever be overcome."
The Pope did, however, praise Mr Bush's "commitment to the promotion of moral values in American society, particularly with regard to respect for life and the family".
Mr Bush's visit coincides with the 60th anniversary of the liberation of Rome by Allied forces.
He is spending two days in Italy before he flies to France for 60th anniversary ceremonies marking the D-Day landings of Allied troops.
The US president has also met Italian Prime Minister Silvio Berlusconi who, unlike the Pope, has been a firm supporter of the Iraq war.
The anti-Bush protests had been "a flop", Mr Berlusconi told reporters while waiting to receive the American president and his wife for dinner.
Mr Berlusconi is among Mr Bush's closest European allies and will give a press conference with him on Saturday.
Despite the opposition of most people in Italy to the war in Iraq, he has repeatedly pledged he will keep Italian troops in Iraq and rejected suggestions that they might leave early.
The Italian government, security forces and the US state department had all warned that violence would mar the protest planned for Mr Bush's visit.
Some anti-war protesters held a peaceful demonstration earlier in the week as Rome celebrated Republic Day with a military parade.
Thousands of protesters from across Italy, many carrying rainbow coloured Pace, or Peace, flags were back on Friday as entire areas of the city were cordoned off.
After the march set off on Friday afternoon, La Repubblica newspaper reported that a group of about 600 youths, with their faces covered and carrying sticks, were also taking part in the march.
TIMETABLE OF EVENTS 6 JUNE
0900 Franco-American ceremony begins at the US cemetery in Colleville
1100 Bi-national service at British Cemetery Bayeux
1430 International march past on cliff top Arromanches
1730 French national ceremony in Ouistream
1730 British veterans march in Arromanches
1820 French German ceremony in Caen
All timings are local
Earlier, masked protesters had set fire to overturned rubbish bins and thrown fireworks at government buildings in a "symbolic" protest against the war.
Mr Bush trip to Europe is seen as an important an opportunity to push for a new UN resolution on Iraq with some key Nato allies face to face.
But recent images of Italian hostages being held in Iraq have reinforced opposition to the war among many Italians, our correspondent says.