OTTAWA — The country's top court has refused to take another look at a multi-billion-dollar damage claim by mentally disabled military veterans who say Ottawa mismanaged their pension benefits.

In a decision released without comment Thursday, the Supreme Court of Canada rejected a request by the vets for permission to argue their case one more time.

The high court had previously ruled, in 2003, that the federal government acted lawfully in passing a 1990 law that barred retroactive compensation to the veterans, most of whom served in the Second World War.

Their lawyers later persuaded an Ontario Superior Court judge that the ruling applied only to accumulated interest, not to other potential damages.

The judge awarded $4.6 billion in a class-action suit launched on behalf of thousands who suffered mental trauma during their wartime service.

But the Ontario Court of Appeal overturned the award last year in a judgment that left the vets empty-handed.

The latest decision by a three-judge Supreme Court panel may deal a fatal blow to any hope of winning compensation through the courts, although the vets will likely continue a political lobbying campaign to put pressure on the Conservative government to meet their demands.