A leading representative of Holocaust survivors in Spain has admitted to being "an impostor".
Spanish Holocaust survivors are outraged by Mr Marco's admission
Enric Marco told Spanish TV he was never held in the Nazi concentration camp of Flossenburg as he had claimed for nearly 30 years.
Mr Marco, 84, was head of the Amical de Mauthausen group, named after the camp in Austria where the Nazis held most of their Spanish political prisoners.
His lies were discovered by a historian researching his story.
Mr Marco admitted: "I wasn't in a concentration camp. I was held in captivity and the Nazis did impose penalties on me. But that does not exonerate me from being an impostor."
He addressed the Spanish parliament in January, at a moving event marking the 60th anniversary of the liberation of Auschwitz.
"When we arrived in the concentration camps... they stripped us, their dogs bit us, their spotlights dazzled us," he said.
"They put the men on one side and the women and children on the other; the women formed a circle and defended their children with their bodies," he added.
More recently Mr Marco attended a ceremony in the Ravensbruck concentration camp in Germany.
'Lie began in 1978'
But on the very day Mr Marco was re-elected president of Amical de Mauthausen, it emerged that he had lied about his past.
Historian Benito Bermejo had noticed inconsistencies in Mr Marco's account while researching Spanish prisoners' experiences in the Nazi death camps.
"He said strange things that did not correspond to the general historical facts," Mr Bermejo told the Efe news agency.
Mr Marco recently visited the Ravensbruck camp
"For example, that he had been arrested and handed over to the Gestapo in Marseille in 1941."
"In that year Marseille was an area of France not under occupation, and normally the Spanish republicans were not handed over to the Germans - that happened later," he said.
Real survivors had been having their doubts, too. Mr Marco had always avoided entering into too much detail when recounting his experiences to them.
On Wednesday he decided to come clean.
"The lie began in 1978," Mr Marco told Efe.
"It seemed I was getting more attention and could better publicise the suffering of the many people who passed through the concentration camps," he admitted, insisting there was no evil intent behind the fabrication.
But Holocaust survivors in Spain are outraged.
Neus Catala, a survivor of the Ravensbruck camp, said Enric Marco was a "traitor".
The stance he took was "an insult to the memory of the dead", she told Efe.
"More than 7,000 Spaniards went to the concentration camps, and most of them died there."
Despite Mr Marco's claim to be raising awareness of the Holocaust, Mr Bermejo warns that his lies could have the opposite effect.
"The danger exists that people who deny the reality of the Nazi camps... might exploit this and tell us that no testimony about the Holocaust has any value," he said.
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