Kirchner, 60, suffered a heart attack and was taken to hospital in the Patagonian town, some 2,800 km southwest of Buenos Aires, in a serious condition. As he checked into Jose Formenti hospital, he was accompanied by his wife.
Doctors tried to resuscitate him, but could not. He had a "cardiorespiratory arrest with sudden death", doctors at the hospital said. Kirchner had already had heart surgery twice this year. In February, he suffered from an obstructed carotid artery, while in September he underwent a angioplasty.
He was regarded as one of the major forces in Argentine politics, and was also a likely candidate in the South American country's 2011 presidential election. Kirchner was the current president of the Union of South American Nations (Unasur) and was believed to have recently played a major part in efforts to keep Ecuadorian President Rafael Correa in the job amid a major police mutiny.
According to media reports, the Argentine government was to hold an emergency meeting in Buenos Aires, amid a national political commotion.
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