Apple accounted for 4.6 percent of the global mobile phone market in the second quarter of 2011, according to figures from analyst house Gartner.

Gartner's figures show that worldwide sales of mobile devices to end users totaled 428.7 million units in the second quarter of 2011, a 16.5 percent increase from the second quarter of 2010.

Sales of smartphones were up 74 percent year-on-year and accounted for 25 percent of overall sales in the second quarter of 2011, up from 17 percent in the second quarter of 2010. Apple's iPhone increased its share of this market from 14.1 percent to 18.1 percent from Q2 2010 to Q2 2011, according to Gartner's figures.

Gartner put this down to the 42 new carriers and 15 new countries that it entered in the second quarter of 2011, which brings its total coverage to 100 countries.

"This expansion caused its inventory to grow a little by the end of the second quarter of 2011, when sales to end users stood at 19.6 million units. In mainland China, Apple is the seventh-largest mobile phone vendor and the third-largest smartphone vendor," Gartner said.

Android, meanwhile, boosted its market share from 17.2 percent in Q2 2010 to a whopping 43.4m in Q2 2011, while Symbian and BlackBerry went in the opposite direction - from 40.9 percent to 22.1 percent and from 18.7 percent to 11.7 percent over the same period, respectively. Microsoft's share of the smartphone market also slumped from 4.9 percent to just 1.6 percent.

"Google and Apple are the obvious winners in the smartphone ecosystem. The combined share of iOS and Android in the smartphone operating system (OS) market doubled to nearly 62 percent in the second quarter of 2011, up from just over 31 percent in the corresponding period of 2010. Gartner analysts observed that these two OSs have the usability that consumers enjoy, the apps that consumers feel they need, and increasingly a portfolio of services delivered by the platform owner as well," the report reads.

Gartner also sounded a warning about smartphone sales in the second half of 2011. "We expect manufacturers and distributors to remain cautious about raising their stock levels in the second half of 2011, following the recent uncertainty on the world financial markets," said Annette Zimmermann, principal research analyst at Gartner.

Overall, Gartner expects sales of mobile devices to grow around 12 percent in 2011.