Groups set fire to police cars and threw stones at police. Police said the clashing groups were made up of pro- and anti-Eritrean government people attending a meeting in The Hague.

"Stones, fireworks and other substances were thrown at police officers and firefighters during the incidents. Some people had weapons in their hands to hit people," police said.

Two police cars and a tour bus were set on fire during the clashes. Four police officers were injured.

Police chief Marielle van Vulpen said officers were confronted with "very intense and serious violence all of a sudden".     

Police reportedly detained some people and appealed to citizens to share witnesses and video footage to deepen the investigation.

Hospital mixed up babies, mother given wrong child Hospital mixed up babies, mother given wrong child

The Hague Mayor Jan van Zanen said violence against police and police vehicles was "unacceptable".

Wilders: Arrest and deport

Far-right politician Geert Wilders posted footage of the events on his social media account with the caption "Arrest and deport".

"Why is half the world allowed to come here, clash among themselves, throw stones at the police and set police cars on fire," Wilders reacted, saying, "I want to be prime minister to bring order to this."According to Dutch official data, 25 thousand Eritreans live in the country.Pro- and anti-government Eritrean groups in the Netherlands have clashed before. There were people injured with knives in the incidents last year.

Recently, there has also been violence at gatherings of Eritreans in other European countries. Last summer, 26 police officers were injured in clashes at an Eritrean festival in Giessen, Germany, while a few weeks later violence broke out at an Eritrean festival in Stockholm, injuring 50 people.Eritrea had gained independence from Ethiopia in 1993. Eritrean President Isaias Afwerki has been in power since the country with a population of 3 million gained independence.Political parties are banned in the country and there are restrictions on freedom of the press and freedom of expression.  The country lacks a parliament, independent courts and civil society organizations.