The Labor Department said its seasonally adjusted Consumer Price Index dipped 0.1 percent last month after falling 0.2 percent in May. Analysts polled by Reuters had forecast consumer prices to be flat last month.
Consumer prices have not declined for three successive months since the period from October to December 2008.
In the 12 months to June, the consumer price index rose 1.1 percent, the smallest advance since October, after increasing 2 percent in May, the Labor Department said. Markets had expected a 1.2 percent increase in June.
(Reporting by Lucia Mutikani, Editing by Chizu Nomiyama)