Former Bosnian Serb leader Radovan Karadzic has been sentenced to 40 years in jail by UN judges who found him guilty of genocide for the 1995 Srebrenica massacre and of nine other war crimes charges.

Karadzic, 70, the most senior political figure to be convicted by the International Criminal Tribunal for the Former Yugoslavia in The Hague, was found guilty of 10 out of 11 war charges. He was acquitted of a second count of genocide in various towns across Bosnia during the war of the 1990s.

Presiding judge O-Gon Kwon said the campaign in which the city of Serbs, Muslims and Croats was shelled and sniped at by besieging Bosnian Serb forces could not have happened without Karadzic's support.

He was also found guilty of deportation, unlawful attacks, inhumane treatment, taking hostages, extermination and he was found criminally responsible for a campaign of sniping and shelling in the siege of Sarajevo.

However, he said crimes had been committed by Bosnian Serb forces against Bosnian Muslims and Bosnian Croats in the municipalities of Bosnia, but that these did not amount to genocide.

Karadzic is the highest-ranking person to face reckoning before the UN tribunal in The Hague over a war two decades ago in which 100,000 people died as rival armies carved up Bosnia along ethnic lines that largely survive today.

Among the main charges is that Karadzic, who was arrested in 2008 after 11 years on the run, controlled Serb forces that massacred 8,000 Muslim men and boys in Srebrenica in 1995 after overrunning the supposed UN-designated "safe area".

Karadzic, who once headed the self-styled Bosnian Serb Republic and held the title of supreme commander of its armed forces, was charged with two counts of genocide, the second for a campaign of purging Bosnian Muslims and ethnic Croats from towns around the country.

The only more senior official to face justice before the International Criminal Tribunal for the former Yugoslavia (ICTY) was the late Serbian President Slobodan Milosevic, who died in custody a decade ago before a verdict was reached.

Ratko Mladic, the general who commanded Bosnian Serb forces, was the last suspect to be detained over the Srebrenica slaughter and is also in a UN cell awaiting judgment.

The Srebrenica massacre and the years-long Serb siege of Bosnia's capital Sarajevo, with which Karadzic is also charged, were events that turned world opinion against the Serbs and prompted NATO air strikes that brought the war to an end.

Karadzic defended himself through his 497-day trial and called 248 witnesses, poring over many of the millions of pages of evidence with the help of a court-appointed legal adviser.

Prosecutors say he conspired to purge Bosnia of its non-Serb population. Rejecting the charges, Karadzic sought to portray himself as the Serbs' champion, blaming some of the sieges and shelling on Bosnian Muslims themselves.

Critics of the ICTY argue that its prosecutors have disproportionately targeted Serbs, with 94 out of 161 suspects charged from the Serbian side, while 29 were Croat and nine Bosnian Muslim.

Prosecutors have also been criticised for not bringing charges over the atrocity-ridden war against two other leaders of that era who have since died -–Croatian President Franjo Tudjman and Bosnian President Alija Izetbegovic.

"If you had got prosecutions of those three (including Milosevic) then you'd get a really good picture of the way the violence was produced but we're not getting it," said Eric Gordy, an expert on the court at University College London.

The ICTY, set up in 1991 at the outset of federal Yugoslavia's violent break-up that killed 130,000 people through the 1990s, was meant to deter future war crimes and promote reconciliation, but its judgments remain divisive.

This week, the government of Croatia – an ex-Yugoslav republic now in the European Union – asked the ICTY to revise a ruling that named Tudjman, the country's founding president, as an accessory to a plan to commit ethnic cleansing in Bosnia.

Many Serbs, both in Bosnia and Serbia, regard the court as a pro-Western instrument, maintain that Karadzic is innocent and believe his conviction would inflict grave injustice on all Serbs.

Serge Brammertz, prosecutor at the tribunal, worries that its work, which is winding down, has done little to help heal the war's deep wounds, given that ethnic nationalists continue to dominate power in much of Bosnia.

"I'm not convinced everyone has really understood the wrongdoings from the past," he said. "Many people in all the former Yugoslavia are still using a rhetoric that is still closer to what we heard in court than we should expect."

Additional reporting by Reuters.