Paris - French police arrested 300 anti-Nato protesters during a summit in Strasbourg marking the 60th anniversary of the alliance, Interior Minister Michele Alliot-Marie said on Sunday.
Thousands of protesters took to the streets on Saturday - police said they numbered 10 000 but organisers put turnout at 30 000 - with radicals setting fire to a hotel, a pharmacy and a disused customs office.
Alliot-Marie said police had been tracking hardcore protesters for several days and "prevented them from committing a certain number of acts of violence" during the two-day summit attended by 28 leaders.
"We carried out 300 arrests," she told RTL radio. "We weren't able to catch all of them because this is a type of urban guerrilla where they commit offenses and then disappear."
Several protesters and eight police officers were injured during clashes, the interior minister said.
The protests in Strasbourg came a few days after a man died during a demonstration in London during the Group of 20 summit.
Masked demonstrators belonging to a hardcore anarchist group called Black Blocks hurled rocks and other objects at police in Strasbourg, smashed windows with metal bars and damages offices during the protests on Saturday.
Alliot-Marie said guests at a hotel had to be evacuated after they set fire to the building.
President Nicolas Sarkozy's chief of staff praised the security operation in Strasbourg and said police were confronted with radicals who "just had one thing in mind: to fight and riot."
"Many came to Strasbourg not to express a dissenting opinion but carrying arms, metal bars and sticks," Claude Gueant told French radio.
"These people go to all of the summits, the G8, the G20, to start riots, to engage in raw violence," he added.
Leaders of the North Atlantic Treaty Organisation agreed during their summit that ended Saturday to provide 5 000 additional troops to Afghanistan to boost security during elections in August and train Afghan security forces.
The interior ministry had said that 10 demonstrators were injured during clashes, most of whom suffered from tear gas inhalation, but the minister declined on Sunday to give a figure.
Several protesters were leaving hospitals in France and across the Rhine river in Germany, saying they suffered injuries during the protest but police have no record of the violence, an interior ministry official said.