IALOVENI, Moldova — A thick carpet of white ash in the back of a burned-out Volkswagen van is all that remains of the final, desperate act in a banking swindle so enormous that it cost this impoverished Eastern European nation the equivalent of an eighth of its annual economic output.

Relative to the modest size of Moldova’s economy, the disappearance of hundreds of millions of dollars from three lenders, now insolvent, could rank among the world’s biggest bank thefts.

The losses have exposed deep-rooted corruption and the shadowy power of feuding business oligarchs who have hobbled European and American efforts to draw former Soviet states out of Moscow’s orbit. The scandal has emboldened and invigorated pro-Moscow forces in the tug of war over former Soviet lands.

Iurie Leanca, Moldova’s prime minister until early this year, said he knew his country’s lenders “were going in the wrong direction” because of huge “toxic loans” to insiders. But little could be done, he said, “because institutions simply do not work here.”