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SAO PAULO, April 23 (Reuters) - Brazilian retailer Carrefour Brasil on Tuesday reported a 2.5% year-on-year increase in its first-quarter gross sales, which totaled 27.8 billion reais ($5.42 billion) in the period.

The company controlled by French retail giant Carrefour said in a securities filing that gross sales of its hybrid wholesale unit Atacadao, which accounts for nearly 70% of group activity, rose 6.6% to 19.3 billion reais.

Carrefour Brasil's retail segment, meanwhile, saw gross sales slip 10.7% to 6.9 billion reais, also considering gasoline sales, as the company closed 123 stores by the end of the quarter as part of a portfolio reshuffle it started late last year.

The company is scheduled to publish its full first quarter results on May 7. ($1 = 5.1265 reais) (Reporting by Andre Romani; editing by Jonathan Oatis)