Sarajevo on Saturday marked 100 years since the assassination that triggered World War I, plunging Europe into the bloodiest conflict it had ever seen and redrawing the world map.

With the people of the Balkans still deeply divided over the legacy of that fateful day, separate commemorations were to be held to mark the occasion.

It was in on a Sarajevo street corner on June 28, 1914, that a Bosnian Serb nationalist shot dead the Austrian Archduke Franz Ferdinand and his wife, setting off a chain of events that sucked Europe's great powers into four years of violence unprecedented in its scale and intensity.

Many of the former foes marked the centenary on the sidelines of an EU summit on Thursday with a low-key ceremony at Belgium's Ypres, where German forces used mustard gas for the first time in 1915.

But the deep Balkan divisions stirred up by the anniversary have made it impossible for heads of state and government to come together at the site of the assassination in the Bosnian capital.

"It would have been impossible to bring everyone (Serbs, Muslims and Croats) together on June 28 in Sarajevo," said the Bosnian Serb historian and diplomat Slobodan Soja.

Wildly differing interpretations of 20th-century history endure in a region where the scars of the wars that marked the break-up of Yugoslavia in the 1990s, unleashing centuries of resentment and divisions, are still fresh.

And a particularly divisive figure is the archduke's assassin, the 19-year-old Serb nationalist Gavrilo Princip.

While the Muslim majority in today's Sarajevo see Princip as a terrorist who unleashed calamity, the Serbs regard him as a hero seeking to liberate the Slavs from the Austro-Hungarian occupier.

Resenting the notion that Serb nationalism was to blame for triggering the Great War, Bosnian Serb leaders have refused to join the main Sarajevo commemorations that will feature a late afternoon performance by the Vienna Philharmonic, a symbolic envoy from the capital of a once-loathed empire.

Instead on Friday they unveiled a two-metre bronze statue of Princip in eastern Sarajevo, and will hold their own early afternoon ceremonies on Saturday in eastern Bosnia and in Belgrade.


'Hero or terrorist'

Until Bosnia's war, Princip was Sarajevo's favourite son -- two years after he died in prison in 1920 his bones were dug up and brought to be buried in the city, which named a bridge after him and put up plaques in his honour.

During the war he was worshipped by the Bosnian Serb forces besieging the city in the 1990s, becoming an all the more loathed figure among the city's trapped Muslim and Croat civilians.

"Within the army bombing Sarajevo, Gavrilo Princip was a cult figure," said the Bosnian Muslim historian Husnija Kamberovic.

After the wars, the plaques honouring were ripped off and the bridge named after him reverting to its pre-1914 name.


'World map redrawn'

Princip's brazen attack 100 years ago dragged almost half the world's population into a cycle of violence of unprecedented scale and intensity.

What became known as the Great War lasted more than 52 months and left some 10 million dead and 20 million injured and maimed on its battlefields, while millions more civilians perished under occupation, through disease, hunger or deportation.

Four of the world's most powerful empires -- Russian, German, Austro-Hungarian and Ottoman -- collapsed as the world map was redrawn and Europe's ruin cleared the way for the rise of a new superpower, the United States.

And World War I fanned the emergence of many of the ideologies that fashioned the 20th century and its conflicts, including anti-colonialism, Communism, Fascism and Nazism.