A German court has thrown out the case against an 89-year-old former soldier over the Nazis' worst atrocity on French soil, the 1944 massacre in the village of Oradour-sur-Glane.

The regional court in the western city of Cologne, citing a lack of evidence, said it would not try the unnamed pensioner who was charged in January with the murder of 25 people committed by a group, and with aiding and abetting the murder of several hundred people.

SS troops slaughtered 642 people in the tiny village in western France on 10 June 1944 during World War II, in a horrific crime that deeply scarred the French nation.

"The court was obliged to examine whether the available evidence would likely be sufficient to prove the crimes with which he had been charged in a trial," it said.

"The court determined with today's decision that this was not the case."

The accused, who was 19 at the time, had acknowledged that he was in Oradour-sur-Glane at the time and a member of the SS, but he disputed any involvement in the murders.

The male victims were mowed down with machine guns in a barn, with any survivors shot at close range with pistols before the barn was set ablaze.

Prosecutors had said that the accused then went to the village church where several hundred women and children were being held prisoner.

Members of the unit used explosives, automatic weapons and hand grenades to kill many of them, before setting the church on fire.

The suspect was accused of abetting the murder by either assuming blockade and surveillance duties within sight of the church or carrying flammable material to the church, prosecutors said.

Among the 642 victims in the village were 254 women and 207 children.

The case had been reopened 70 years later based on a review of earlier investigations by German prosecutors.

The charges were part of a twilight bid by the German justice system to prosecute crimes committed under the Nazis.

However, the advanced age of the suspects and the difficulty of establishing criminal proof seven decades on has meant that few of the defendants have gone on to serve time in prison.