Large protests have been taking place as the far-right Alternative for Germany (AfD) party opened its convention in the western city of Essen, with demonstrators attempting to block roads and clashing with police.

Police used pepper spray and batons on Saturday to push back protesters attempting to break through a cordon before the two-day event kicked off, a police spokesperson told the German news agency dpa.

Masked demonstrators attacked officers, according to police, who reported “several” arrests. About 1,000 police have been deployed in Essen.

“Several disruptive violent actions occurred … demonstrators, some of them hooded, attacked security forces. Several arrests were made,” police in North Rhine-Westphalia state, where Essen is located, said on X.

Up to 100,000 protesters are expected to take part in counterdemonstrations and other events in Essen, dpa reported. The authorities have raised concerns that while most could be peaceful, about 1,000 leftists would use violence to disrupt the congress.

Leftist groups warned of blockading entrances to the venue to prevent AfD delegates from entering.

Some 600 delegates are meeting, with the party’s current co-leaders Alice Weidel and Tino Chrupalla seeking re-election ahead of Germany’s parliamentary polls next year.

Weidel told delegates as she opened the meeting that “what is going on out there has nothing to do with democracy”, adding that “we are here and we will stay”.

“We have the right like all political parties – to hold a congress,” she added.

The AfD took 16 percent of the vote to finish second in the European Parliament elections earlier this month despite a series of scandals and setbacks.

The party was expelled from the Identity and Democracy (ID) Group in the European Parliament in May following comments by its lead candidate Maximilian Krah to an Italian newspaper that the members of the Nazi paramilitary SS force were “not all criminals”.

While the AfD banned Krah from campaigning, the party was already under scrutiny over allegations that it harbors agents for Russia and China. One of his aides was arrested on suspicion of spying for China.