By Pavel Polityuk and Jack Stubbs
KIEV/ROSTOV-ON-DON, Russia (Reuters) - Protests prompted a Ukrainian court to postpone its questioning of exiled former president Viktor Yanukovich as a witness at a trial on Friday over the killing of demonstrators, a delay that Yanukovich said was a bid to obstruct justice.
The court was due to cross-examine Yanukovich via video link over the fatal shooting by police officers of protesters during the Maidan street revolt of 2013/2014 when he was president, unrest that culminated in him fleeing to Russia.
It would have been the first time Yanukovich has been interrogated by a Ukrainian court about the deaths, but his role as a witness in the trial of five riot police officers, rather than standing accused himself, has angered many in Ukraine.
A small crowd of protesters in Kiev - some clad in camouflage and waving nationalist flags - prevented the defendants from being transported to the courthouse from jail.
After some debate in the courtroom over how to proceed in the absence of the accused, the judge postponed the testimony to Nov. 28, despite appeals from Yanukovich to carry on.
"I am outraged by what happened," he told journalists in the Russian city of Rostov-on-Don, saying right-wing radicals had disrupted the event with the tacit approval of the Ukrainian authorities to cover up the truth of what happened at Maidan.
Later, during a lengthy briefing in which he quoted philosopher Friedrich Engels and U.S. statesman Henry Kissinger, Yanukovich reasserted his innocence and presented three thick volumes that he said contained evidence of what really happened during the uprising.
Ukrainian General Prosecutor Yuriy Lutsenko said the Kremlin has allowed Yanukovich to be cross-examined merely as a public relations stunt, pointing to Russian insistence the testimony coincide with the third anniversary of the protests.
Yanukovich escaped Kiev in the final days of the uprising, which installed a pro-European leadership and lit the fuse for Moscow's annexation of Crimea and a separatist conflict in the mainly Russian-speaking east.
More than 100 demonstrators were killed in the three months of street protests in Kiev's Maidan square - 48 allegedly gunned down by police snipers who Ukrainian authorities say received direct orders from Moscow-backed Yanukovich.
Yanukovich is himself being investigated on suspicion of mass murder, but the current trial is of five "Berkut" riot police accused of carrying out the shooting. They have pleaded not guilty.
Three years on from the start of the protests, nobody has yet been held accountable for the deaths - an additional pressure on the Ukrainian authorities' public approval ratings, which have been driven down by the patchiness of efforts to root out corruption and improve the economy.
Moscow says the 2013/14 uprising was orchestrated by the West and questions the legitimacy of the post-Yanukovich leadership in Kiev.
(Writing by Alessandra Prentice; editing by Matthias Williams and Robin Pomeroy)