WASHINGTON - Sen. Barack Obama misspoke when he told a group of veterans that his uncle was among the troops who liberated the Auschwitz concentration camp, aides to the Democratic presidential candidate said Tuesday.

In fact, Obama's great-uncle took part in the liberation of one of the concentration camps at Buchenwald, spokesman Bill Burton said.

Obama "mistakenly referred to Auschwitz instead of Buchenwald in telling of his personal experience of a soldier in his family who served heroically," Burton said.

Critics were quick to seize on the mistake.

"It was Soviet troops that liberated Auschwitz, so unless his uncle was serving in the Red Army, there's no way Obama's statement yesterday can be true," said Republican National Committee spokesman Alex Conant.