Apple's share of the smartphone market dropped in the second quarter to its lowest level in three years.

According to research firm Strategy Analytics, the share of the iPhone slipped to 13.6% in the quarter from 16.6% in the same quarter last year. The largest vendor Samsung, however, saw its share soar to over 33% from more than 31% in the same period. Samsung shipped over two times the number of smartphones Apple did in the quarter, Strategy Analytics said.

Apple is at risk of being trapped between 3-inch Android smartphone models at the low end and 5-inch Android models at the high end, the research firm said yesterday. The market share of the iPhone in the second quarter was the lowest since the second quarter of 2010, it added. In contrast, Samsung saw strong demand in China and other countries for its flagship Galaxy S4 device, which helped increase volumes.

Sales of the iPhone hit 31.2 million in the April to June quarter, a record for the period, Apple said earlier this week. It had sold 26 million phones in the same quarter last year.

Overall, smartphone shipments grew 47% year-on-year to reach a record of 230 million units in the second quarter of 2013, Strategy Analytics said. LG had a share of 5.3%, while ZTE had 5% and Huawei Technologies had 4.8% of the smartphone market. The research firm listed other vendors as together having a share of 38.2% in the quarter.

IDC reported a 52.3% growth in the smartphone market with 238 million units shipped in the second quarter. Buyers may have postponed iPhone purchases expecting the launch of a next-generation device in the fall, it added. Apple's sales could accelerate globally if it launches a lower-cost iPhone and continues to penetrate prepaid markets in the quarters to come, IDC said.

The worldwide mobile phone market grew 6% year-over-year in the second quarter of 2013 to over 432 million units, according to IDC. Strategy Analytics said shipments reached 386 million units, an increase of 4% year-on-year.

The research firms did not immediately comment on the reason for the variations in their estimates.

Nokia's share dropped in the handset market to 15.8% as its shipments fell 27% to about 61 million in the second quarter, said Strategy Analytics. The Finnish vendor was hit by "fading Symbian smartphone volumes and lackluster feature phone demand," as it continued to struggle in the big three markets of China, US and India, the research firm said.