Fan violence mars PSG title celebrations in Paris
Celebrations to mark Paris Saint-Germain's first French football league title in 19 years have been marred by clashes between fans and riot police.
At least 30 people were injured, including policemen, and 21 arrests were made after the unrest on Place du Trocadero, near the Eiffel Tower.
It took 800 police several hours to bring the situation under control.
Interior Minister Manuel Valls has banned a trophy presentation due outside the City Hall on Wednesday.
Defending police actions, he said PSG had "serious problems with its fans". "Football is still sick - that's the case with PSG," he told Europe 1 radio.
He suggested that trouble could have been avoided had the celebration taken place in the club's home stadium, Parc des Princes.
Monday's riot comes three years after a PSG fan was killed outside the stadium.
The club changed its ticketing policy and temporarily banned supporters' groups from the stadium following the death, angering many Ultras, as the club's hardline supporters are known.
The clashes erupted after some 10,000 fans had to wait more than an hour for PSG players to arrive on the square.
Within five minutes of appearing on the podium, and before either coach Carlo Ancelotti or captain Thiago Silva could address the crowd, the team were led away.
Riot police moved in and fired tear gas after smoke bombs and various objects were thrown, and the fans surged towards the players' podium, officials said.
A banner saying "Freedom for the Ultras" was also unfurled from the Palais de Chaillot.
Order was only restored on the nearby Champs-Elysees after midnight, AFP news agency reports. During the evening, restaurants on the avenue including the famous Fouquet's closed early because of the unrest.
AFP's correspondents in the Trocadero area found three cafes with their windows smashed, a broken bus shelter and several damaged cars.
Dismay at events in the capital dominated French media on Tuesday morning.
"A few troublemakers were enough to spoil the party for which PSG and Paris had been waiting for 19 years," wrote Le Parisien.
"Such a long wait and such a fiasco," was how Le Figaro put it.
Mr Valls, who was accused by conservative opposition politicians of "unacceptable inertia" and "amateurism", said the violence had presented an "intolerable image of Paris and France".
"We must be merciless with these individuals who indulge in violence," he added.
The interior minister said he wished to meet the club's managers to discuss the event.
Paris police commissioner Bernard Boucault said there would be no "more events like this in a public place for Paris Saint-Germain".
The club issued a statement, which said the party had been "spoiled by a few hundred troublemakers who have nothing to do with football".
"Paris Saint-Germain is more determined than ever to build a huge European club, worthy of the French capital," it added.