Google Inc. displaced Apple Inc. in the first quarter to become the second most popular smart phone provider, Reuters reported.

According to NPD Group Inc., smart phones featuring Google’s Android operating system accounted for 28 percent of U.S. smart phone unit sales, while Research in Motion Ltd.’s BlackBerry phone led the way with a 36 percent market share.

The latest sign of the increasing competition in the growing smart phone operating system market, Apple’s iPhone dropped to third place in the first quarter, as its share remained flat quarter-over-quarter at 21 percent.

Ross Rubin, an NPD analyst, said promotions by Verizon Wireless helped Google in its strong first-quarter showing of Android phones.

“As in the past, carrier distribution and promotion have played a crucial role in determining smart phone market share,” he said in a statement.

Apple, whose iPhone is available exclusively on the AT&T Inc. wireless network, has sold more than 51 million of the devices since their launch in 2007.

Increasingly replacing utilitarian cellular phones, smart phones allow consumers to surf the Web, send e-mail and run customized applications on large color screens.