* U.N. tribunal has cost in excess of $1 billion
* Court quashed convictions against two ministers this week
* Rwanda prosecutor says court dismantling its legacy
By Jenny Clover
KIGALI, Feb 8 (Reuters) - The U.N.-backed war-crimes court trying chief Rwandan genocide suspects risks going down as a $1 billion white elephant, Rwandan officials and a survivors group said after the court overturned the conviction of two former ministers.
Prosecutor General Martin Ngoga warned people in Rwanda, a country ripped apart along its ethnic seams by the 1994 massacre, were in "serious disagreement" after the tribunal quashed 30-year jail terms handed down to the ex-politicians.
One genocide survivors' group said the Tanzania-based International Criminal Tribunal for Rwanda (ICTR) appeared to be slowly liberating convicted members of the then-government.
More than 800,000 ethnic Tutsis and moderate Hutus were slaughtered during a three-month killing spree by Hutu extremists that followed the fatal downing of a plane carrying President Juvenal Habyarimana.
The east African country's incumbent President Paul Kagame has been widely hailed by Western powers for fostering stability and development, but for many Rwandans the scars still run deep.
"It's worrying because the trend is pointing at exonerating political leadership from the responsibility of the genocide," a visibly irritated Ngoga told a news conference this week.
"We shall end up with a situation where the tribunal has convicted the rank and file and left out the real big fish."
Justin Mugenzi and Prosper Mugiraneza were convicted in September 2011 of conspiracy to commit genocide and direct and public incitement to commit genocide and jailed for 30 years.
The pair had been part of a case involving high-ranking officials, including the former health minister, Casimir Bizimungu, and former foreign minister, Jerome-Clement Bicamumpaka, who were acquitted in 2011.
An appeals court at the ICTR noted errors in the trial chamber's assessment of evidence, ordering Mugenzi and Mugiraneza's immediate release.
"As far as Rwandans are concerned, (the ICTR is) dismantling its image, its legacy," Ngoga said.
"WHERE ARE THE ACHIEVEMENTS?"
Based in the sleepy town of Arusha at the foot of Mt. Kilimanjaro, the tribunal was at the centre of efforts to set new standards in international justice.
Critics of the tribunal say it has been slow and costly. Some have also questioned its focus solely on the Hutus who led the genocide against minority Tutsis and not on any war crimes that might have been committed by the other side.
Roland Amoussouga, a spokesman for the ICTR, said the court had sent a clear message that no one was above the rule of law. Judgments, he said, were based on fact and law alone.
"We are not a political court, we are a court of law," Amoussouga said by telephone.
The court had been due to wind up "first instance" trials in 2008 and appeals in 2010, but is now due to close down in 2014. It has cost more than $1 billion.
Monday's verdict means just 58 have been jailed by the court for crimes related to genocide. Fifteen of those have appeals pending. A dozen individuals have been acquitted and nine indictees remain at large.
Three of the fugitives are considered to be among those most responsible for planning and executing the massacre. If caught, they will now not be tried by the ICTR, though their cases would still likely be heard by an international tribunal.
Naphtal Ahishakiye of the genocide survivors' organisation Ibuka acknowledged the court was tackling cases that were tough to prosecute, but expressed disappointment.
"Where are the achievements for the big budget that they had?," Ahishakiye said.
The tribunal was losing the respect of Rwandans, Ngoga said.
"I will not be surprised if in the several appeals that are pending and involve cabinet ministers, if they are also acquitted," Ngoga said. (Editing by Richard Lough and Jon Hemming)