Updated

Protesters have injured one police officer while trying to block the hotel in Cologne where the nationalist Alternative for Germany party is holding a two-day convention.

The German news agency dpa reported Saturday that AfD party members could enter their convention center only with massive police protection because hundreds of demonstrators tried to keep them out.

Around 50,000 left-wing protesters are expected and about 4,000 police officers are on the ground in Cologne to prevent a violent escalation of anti-populist rallies.

The convention takes place days after AfD's co-leader Frauke Petry, who is Germany's best-known nationalist politician, said that she won't be her party's top candidate in the September general election, a decision that appears to reflect a growing split among its leading figures.