Argentina and Chile were ruled by notorious military dictatorships in the 1970s, but civilian governments in both countries have increasingly prosecuted decades-old human rights cases.
Guillermo Duret, 56, entered Chile on September 25 with a tourist visa, the day after Argentina's criminal court of appeals sentenced him to 15 years prison for the disappearance of Carlos Labolita, a Peronist militant, overturning an earlier verdict, the newspaper El Mercurio reported.
He was detained on Tuesday in the city of Talca, 350 kilometres (220 miles) south of Santiago, and was to be turned over to Argentine authorities later Wednesday, an official who asked not to be identified told AFP.
The governor of Maule, the region where Duret was detained, signed the order for his expulsion to Argentina.
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