Cologne, Germany - An anti-mosque demonstration in one week's time in Germany is likely to attract 1,500 rightists from around Europe, according to an organizer, Markus Beisicht, in Cologne on Friday as fears grew of violent clashes.

Riot police throughout North Rhine Westphalia state have been put on standby to separate the rightists from up to 40,000 opponents.

The two groups are at odds over the start of building work for Cologne's grand mosque.

The right-wing Pro Cologne group rejects the house of worship for the city's large Muslim community as alien.

Jean-Marie Le Pen, the founder of the anti-immigration National Front in France, will be one of the speakers at the Pro Cologne rally.

Violent leftists are expected to try to disrupt the rally, while trade unions have also rallied to the side of the Muslim community and organized a peaceful mass counter-demonstration.

Beisicht, who is Pro Cologne's chairman, said at least 1,500 people would attend the main rally of his "Congress Against Islamicization" on a downtown square, the Heumarkt.

The Vlaams Belang party in neighbouring Belgium would send hundreds of supporters to cheer their leader Filip Dewinter. Heinz-Christian Strache, head of the right-wing Freedom Party of Austria, would also address the rally.

The weekend event would be launched with a Friday news conference and a city tour to Muslim districts of the city including the grand mosque site. Pro Cologne is hostile to immigrants and campaigned against building permission being granted for the mosque.

Beisicht said the tour would pass the office of "our opponents," the Ditib organization which builds mosques for Turkish-speaking Muslims all over Germany. The city gave planning permission this month for the mosque, which will have a dome and two minarets.

Commenting on leftists' plans to hold sit-ins to block roads around the venue, Beisicht said he was confident "the majority of our participants will be able to reach Heumarkt without harm."

His group had devised ways to move in small groups to evade the leftists.

While Pro Cologne is separate from Germany's far-right parties, state police have put it under surveillance so as to follow up suggestions that it may be an extremist organization. (dpa)