* Tied to shootings of civilians after 1956 uprising crushed
* Biszku denied all charges, appealing conviction
* First former senior Communist tried in Hungary (Adds detail, quotes, context, background)
By Krisztina Than
BUDAPEST, May 13 (Reuters) - A 92-year-old former senior Hungarian Communist Party official was convicted on Tuesday of war crimes over shootings of civilian protesters after the November 1956 uprising that was crushed by Soviet tanks.
It was the first trial of an ex-top communist in Hungary since the government of Prime Minister Viktor Orban, a staunch anti-communist, enacted a law in 2011 to enable prosecution of crimes committed after the anti-Communist revolt.
More than two decades after the fall of Communism, Bela Biszku was charged over his role on a party committee prosecutors said was involved in ordering the shootings of several civilians during protests in Budapest and in the town of Salgotarjan in December 1956 in which dozens of people died.
A Budapest court sentenced Biszku to five-and-a-half years' imprisonment. The prosecution, which had sought a life sentence, said it would lodge an appeal.
"Bela Biszku is guilty of war crimes committed as an abettor (of) homicide against more than one person," Judge Szabolcs Toth told the packed courtroom. For his part, Biszku denied all charges and his lawyer said the verdict would be appealed.
The 1956 uprising against Hungary's Soviet-backed government represented the first major threat to Moscow's grip on Eastern Europe since the end of World War Two.
Hundreds of people were executed and tens of thousands imprisoned after the revolt was put down.
Biszku was also convicted of charges including public denial of the crimes of the former Communist regime and possessing unauthorised ammunition after 11 pieces of hunting ammunition were seized during a house search.
Biszku said in written testimony read out in court that he took no part in any decisions to disperse peaceful rallies by force. His lawyer, Gabor Magyar, said there was no evidence against him and that the case was politically motivated.
Biszku, who served as interior minister from 1957 and 1961, sat through the seven-hour trial, listening attentively. When asked whether he could face sentencing or was too tired and preferred to see it postponed, he replied, "Let's finish it up."
Prosecutor Tamas Vegh said Biszku and other senior Communists used the militia for revenge operations after the uprising and for shoring up their grip on power.
"In this period, there were no more armed clashes. But people had not yet bowed to the new power. The defendant and his accomplices wanted to achieve this and they succeeded, by deploying armed militia," he told the court.
Vegh said that even though it could not be proven that any direct order had been issued to militia to shoot at protesters in Salgotarjan, there was an "ideological order to shoot" as the militia felt empowered to use force.
Biszku's lawyer said militiamen received no orders to shoot at demonstrators. "The situation is that in the several thousand pages of documents read out, there is no sign of any decisions by the (party) committee that volleys must be fired into unarmed crowds," Magyar told the court.
(Editing by Mark Heinrich)