BELGRADE, Serbia (AP) -- Thousands of black-clad young men rampage through downtown Belgrade, hurling Molotov cocktails and stun grenades at police trying to protect a gay-rights march. Soccer fans throw flares and fireworks onto the pitch during a championship qualifier match, forcing its cancellation.
A recent surge in attacks by right-wing extremists is pitting Serbia's pro-Western government against a movement that publicly aims to destabilize the administration and derail its hopes of joining the European Union.
The movement is a blend of violent soccer fan clubs and officially registered far-right "patriotic" organizations with long-standing ties to nationalist politicians and organized crime.
Using unemployed, angry youths as foot soldiers, the groups espouse hatred of minorities and anger at the West over its actions against Serbia during the Balkans wars of the 1990s, including the NATO bombing of Serbia over its crackdown against ethnic Albanian separatists in Kosovo.
Their numbers swollen by rising unemployment, the groups' members have become fixtures of life on the outskirts of Belgrade. Mostly poorly educated men in their 20s, they sport shaven heads and heavy tattoos - often religious images or historic dates related to Kosovo, which they see as Serbia's heartland.
Many wear large wooden Serbian Orthodox crosses around their necks and carry baseball bats, iron bars and knives.
More than 150 people were hurt Sunday as thousands of extremists fought running battles with police trying to protect a gay-pride march. The march was promoted by the government as a sign that Serbia is ready to protect human rights valued by the EU.
The rioters attacked ruling party headquarters, state television company and liberal media outlets. They received support from nationalist politicians who blamed the violence on the government for allowing the gay parade.
EU officials said that the anti-gay riots could hurt Belgrade's bid to join the bloc. Serbian far-right groups warned of fresh violence if the government fails to respond to demands including abandoning its EU goals.
"We are hoping and appealing on the government to take our warning seriously ... to avoid a future wave of violence," said Vladan Glisic of the group Dveri, which claims to advocate traditional Serb family values and religion.
Serbia's top security body, the National Security Council, said Thursday that rioting extremist groups have tried to create instability and unrest, but insisited the country remains stable. Parliament's security board said authorities must further curb extremist groups and punish all those who took part in the rioting, but agreed that Serbia's constitutional order had not been jeopardized.
The U.S. private intelligence company Stratfor said, however, the surge of the far-right in Serbia could spell trouble in the Balkans.
"An ultranationalist Serbia could wreck havoc on European and U.S. priorities," the group said in its report.
An Italy-Serbia European championship qualifier game was abandoned Tuesday in Italy when Serbia fans threw flares and fireworks onto the pitch, burned an Albanian flag and broke barriers - a day before the Netherlands was to decide whether to approve Serbia's continued EU membership talks.
Among the arrested Serbian fans in Italy was the alleged ringleader of the riots, Ivan Bogdanov.
In addition to being the leader of the notorious "Ultra Boys" Red Star Belgrade soccer fan club, Bogdanov is also a member of Movement 1389, named after the historic Serb battle against Ottoman Turks in Kosovo. He was charged with taking part in the burning of the U.S. Embassy in Belgrade in 2008 when the nationalists protested American support for Kosovo's secession from Serbia, according to Serbian court documents.
The 30-year old has been arrested five times on different charges, including drug trafficking and attacking the American Embassy, but was released pending the trials.
"We arrest these people, but they soon walk out free because of a slow judiciary," Serbia's police chief Ivica Dacic complained Thursday.
The initial sign of the violent breakup of the former Yugoslavia came in 1990 when Red Star supporters clashed with Dinamo Zagreb hooligans in the Croatian capital of Zagreb.
The Serbian fans were led by gang boss Zeljko Raznatovic, known as Arkan, who later recruited the Red Star fans to his Tigers paramiliaries who carried out atrocities in Croatia and Bosnia. After being indicted for crimes against humanity by a U.N. tribunal, Arkan was assassinated in a Belgrade hotel in 2000.