Pro Cologne said it held the third day of the event out of the public eye on premises in the nearby city of Leverkusen. It was not clear how many people were attending.

On Saturday, 50 rightwing extremists gathered on a city square under a "Stop Islam" banner and police said another 300 had been unable to attend because streets were blocked by rioting leftists as well as a peaceful sit-in.

Another 100 to 150 rightwing extremists arrived by air at Cologne's airport Saturday but were advised by police to stay there because their safety could not be guaranteed.

Police banned the rightwing rally at the last minute on public-safety grounds.

The counter-demonstrators, including thousands more citizens gathered a kilometer away in support of the mosque, let out a jubilant cheer when the mayor of Cologne, Fritz Schramma, told them the right was beaten.

But the violence was not over. About 6,000 stayed on to hear a pop concert on the street and extreme leftists, who have a deep enmity towards the police, kept scuffling with police or setting garbage alight in the city's alleys.

Baton-swinging police surrounded 500 masked leftists at one point and took the names of individuals who had been seen earlier rioting, throwing stones and firecrackers at officers and trying to snatch away police guns.

Cologne police said they would analyze pictures of the violence Saturday to identify the violent leftists who threw cobblestones and firecrackers at riot police and tried to seize their guns during the mayhem.

Six police were injured, 15 leftists were arrested and 500 were briefly held for identity checks Saturday.

The anti-mosque gathering has not only inflamed passions in Germany, but in Muslim nations.

Iran demanded that Germany prohibit it in advance but German police and lawyers said it could not be banned purely because of the opinions to be expressed. The last-minute ban was justified by the danger to the rightwing extremists.

"We can't allow a few hundred people to deliberately enter a battleground," a police spokesman said.

Police chief Klaus Steffenhagen added, "It would have been excessive to deploy water cannon and special units to fight a way into the square for 300 participants."

Pro Cologne voiced outrage at the ban. Its secretary, Markus Wiener, said, "It's typical of the Cologne police leadership that they can't enforce freedom of assembly and that they cave in to street terrorism."

Wiener said his group had had 1,000 supporters trying to attend the rally.

A city councilor for the group, which won 5 percent of votes at the last poll, said his group would challenge the ban in court. "We'll repeat the event later," Manfred Rouhs told WDR television.

There was no sign in the city of prominent far-right individuals from abroad who had been invited, such as Jean-Marie Le Pen, the founder of the National Front in France.

Schramma, who has personally backed the mosque project, welcomed the rally ban. And praised the peaceful section of the demonstrators, saying they had deployed "keenness, humor and intelligence" to stand up to "racist idiocy."

"It's a victory for the city of Cologne and a victory by the democratic forces in this city," he told DPA.

Armin Laschet, minister for minorities in North-Rhine Westphalia, went further, telling the Tagesspiegel newspaper it was the first time an entire German city "stood up to protect its Muslims."

The mosque, which is to have a dome 37 meters high and two minarets stretching up 55 meters, has been hotly discussed in Cologne, where Turkish-speaking Muslims are a part of what Schramma calls "the city of 180 nations."

Ditib, an Ankara-funded organization that builds mosques all over Germany, says the current mosque at its national headquarters in Cologne is too small for congregations.

Pro Cologne, which won 5 percent of votes at the last Cologne city council election, claims that Turkish-speaking Muslims are "Islamifying" the city by building a mosque with 55-meter minarets.

DPA/Expatica