Up to 100,000 protestors are expected to descend on Essen on Saturday as the far-right Alternative for Germany (AfD) holds a two-day congress to elect its new executive, police in the western Germany city predicted.
The authorities raised concerns that, while most of the expected demonstrations would be peaceful, around 1,000 leftist extremists would use violent means to disrupt the congress.
Around 600 AfD delegates are meeting in the city's Grugahalle indoor arena, with current co-leaders Alice Weidel and Tino Chrupalla seeking re-election ahead of German parliamentary elections in the autumn of next year. Nobody has come forward to challenge the duo.
Leftist groups have announced they intend to blockade entrances to the venue in the morning with the aim of preventing AfD delegates from getting through. Police have made clear that this will not be tolerated.
Police were out in force around where the congress will be held in Essen on Friday and will be deployed again for the duration, they said. The main protests are scheduled for Saturday, with a march setting out from the central station.
At least 45,000 demonstrators are expected to gather on a parking area near the congress venue on Saturday afternoon.
A major theme for the congress is set to be the AfD's campaign in the elections to the European Parliament held at the beginning of June, in which the party did less well than pre-election polling had suggested.
The final stages of the campaign were overshadowed by how the party dealt with lead candidate Maximilian Krah, his controversial comments on the Nazi era and possible links between his assistant and China.
The AfD was expelled from the Identity and Democracy Group in the European Parliament in response to Krah's remarks on the wartime German SS.
