Apple has ousted Nokia as the world's largest smartphone maker as global mobile phone market grew more than 11.3 percent in the second quarter of 2011, according to two separate market research studies.

After becoming the largest smartphone vendor in terms of revenue and profits, Apple has become the world's largest smartphone vendor by volume with 18.5 percent market share, said the latest research from Strategy Analytics released on Friday.

The Cupertino, California-based company sold 20.3 million iPhones in the second quarter,up 142 percent compared with the same period a year earlier.

Samsung's shipments of 19.2 million units grew a huge 520 percent year over year, accounting for 17.5 percent global smartphone market share in the second quarter of 2011.

Apple and Samsung overtook long-time volume leader Nokia for the two spots. The Finnish mobile phone giant accounted for 15.2 percent of global smartphone market share in the last quarter, which is less than half of what it was just one year earlier.

In the second quarter of 2010, Nokia was the No.1 smartphone maker by volume in the world with 38.1 percent of market share. The industry is now waiting Nokia's pending transition to Windows Phone 7.

According to a separate report by International Data Corporation (IDC) released on Thursday, the worldwide mobile phone market grew by 11.3 percent year over year in the second quarter of 2011 despite a decline of the feature phone market for the first time in almost two years.

The feature phone market was down by 4 percent in the last quarter, said the IDC Worldwide Mobile Phone Tracker report. It noted that the decline in shipments was mainly in economically mature regions, such as the United States, Japan and Western Europe, as users making rapid transition to smartphones.

The shrinking feature phone market had a great impact on some of the world's largest suppliers of mobile phones, such as Nokia, which is losing share in the feature phone category to low-cost suppliers, said the report.

For the overall market, global mobile phone vendors shipped 365. 4 million units in the second quarter, compared to 328.4 million units in the same period last year, with Nokia still holding the top spot with a market share of 24.2 percent, followed by Samsung, LG Electronics, Apple and ZTE.

But the 11.3 percent growth was lower than IDC's forecast for the quarter and also below the 16.8 percent growth in the first quarter of 2011.

IDC said the feature phone forecast isn't expected to be any rosier in the future and the shipment growth of feature phones won 't exceed 1.1 percent in the coming years.