Hundreds of gay and human rights activists at Serbia's gay pride event have called for solidarity with migrants passing through the Balkan country in search of a new life in Western Europe.

The pride march was held Sunday in the capital Belgrade under tight security with thousands of riot police in full gear deployed in the downtown area to protect the gathering.

Police say several extremists have been detained. In 2010 extremist groups and soccer hooligans attacked a pride march in the conservative Balkan country, triggering clashes that left more than 100 people injured.

A banner held at the march Sunday read "Europe, Open Your Gates" to the migrants fleeing war and poverty in their home countries.