BUENOS AIRES, Jan 12 (Reuters) - Argentina's annual inflation hit its highest rate in more than 30 years last month as prices almost doubled versus a year ago, official data released on Thursday showed, further eroding consumers' dwindling purchasing power. The annual rate marks the fastest clip of rising prices in more than three decades, or since 1991, according to INDEC. Argentina is battling one of the highest inflation rates in the world as soaring prices hamper growth and force shopkeepers to constantly update price tags. In a recent interview, Economy Minister Sergio Massa projected December inflation would not exceed 5%, adding that monthly increases should edge down to around 3% by April. "It's a psychological factor that wears you out because... wages do not increase like inflation increases," said Aurelio Narvaja, a 41-year-old teacher.

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