Serbia rallied its people on Thursday for a mass protest against Kosovo's declaration of independence to show the world its anger at the loss of its religious heartland.

Organizers expect hundreds of thousands to attend the People's Rally in the capital Belgrade, in what would be the biggest demonstration since half a million filled the streets in 2000 to oust nationalist autocrat Slobodan Milosevic.

Belgrader Milan Vukosavljevic said it was important to show the strength of Serbian felling against Kosovo's independence, which most see as an illegal move despite Western backing.

It's an invented state, shame on Europe and on the whole world, he said.

Analysts said the motivation was more bitterness and frustration than the virulent nationalism harnessed by Milosevic to lead Serbia into disastrous wars with its fellow Yugoslav republics in the 1990s.

A three-storey-high stage was being erected in front of the 100-year-old Yugoslav parliament building, with flags and a giant Kosovo is Serbia banner glinting in the bright sunshine.

The government condemned hooded rioters who stoned the U.S. and EU embassies right after Kosovo said it was seceding on Sunday, but is firmly behind Thursday's march.

State television RTS said 5,000 buses would be mobilized along with free trains to bring people from across Serbia to the 5 p.m. (11 a.m. EST) rally, followed by prayers in the city's biggest Orthodox cathedral.

We must have a rally, but I don't think it will change anything, passer-by Vera Popovic told Reuters television.

Protests were also expected in north Kosovo, where NATO-led peacekeepers reinforced border patrols ahead of a planned rally to a border crossing by army veterans from Serbia.

In the Serb Republic, the ethnic Serb half of Bosnia, several hundred people threw stones at the U.S. consulate in the main city Banja Luka and burned German and French flags.

BE PATRIOTIC!

Serbia has protested in world forums with Russian support, sent envoys home from Washington and European powers that recognized Kosovo, and championed Serbs who dominate a northern strip of Kosovo. But there is little else it can do in practice.

It has said it will not resort to violence to try to regain the province it lost to U.N. control when a NATO air war forced its troops out in 1999.

For the state-sponsored rally, schoolchildren have the day off, and media have been asked to be patriotic.

Everyone to the rally!, said the tabloid Pravda over a picture of a ruddy-cheeked child clutching a Serbian flag.

Kosovo is a highly emotive issue for Serbs, who know their southern province from songs and stories that highlight its role as the birthplace of a glorious medieval kingdom.

A tenth of Serbia's territory, its long-term Albanian majority rejects Serbian rule, pointing to its crackdown on a 1998-99 insurgency that killed some 10,000 people and forced hundreds of thousands from their homes, prompting NATO to act.

Serbia has said it will never accept its loss, and counts on Russia to block its admission to the United Nations.

The anger Serbs feel right now is understandable, it's part of the process that comes before acceptance, a Belgrade-based Western analyst said on condition of anonymity.

But long-term prospects for Serbia are very good, if the West is patient and lets them go through this difficult time.

(additional reporting by Olja Stanic in Banja Luka; Editing by Richard Meares)