Worldwide smartphone sales grew 19 percent in the first quarter of 2015, according to research.

The report from Gartner shows that worldwide sales reached 336 million units, driven by strong sales in emerging markets, excluding China.

The fastest growth was seen in emerging Asia/Pacific, Eastern Europe, the Middle East and North Africa, driving an overall 40 percent increase in sales in emerging markets in the quarter.

The quarter also saw Apple become the biggest smartphone vendor in China for the first time, beating Xiaomi. iPhone sales rose 72.5 percent in Q1. Greater China is now Apple’s largest volume market, ahead of North America.

Samsung, meanwhile, saw a decline in sales and share in the quarter. Apple is closing in on its rival, with the gap between them falling from 40 million units to 20 million units year-on-year.

"Despite a weak first quarter globally, Samsung’s performance returned to growth quarter-on-quarter, with an 11 per cent increase from the fourth quarter of 2014," commented Anshul Gupta, research director at Gartner.

Gupta added: "We expect Samsung’s drop rate to be slower than that seen in recent quarters with sales of its new S6 smartphones starting in the second quarter of 2015, and its Galaxy Alpha receiving good response."

Gartner research director Roberta Cozza commented: "I think Samsung will continue to find it difficult this year and if they don’t add value to their hardware beyond technology then they could continue to lose share, not only to Apple but to other vendors. They need to extend the value that is attached to the hardware."

Q1 2015 also saw Android‘s share falling by 1.9 percent in the smartphone operating system market, while iOS grew year-on-year by 2.7 percent.

Another notable trend in the quarter was a general slowdown of growth in the Chinese market, which showed a growth rate similar to Europe, suggesting saturation. Chinese brands could target the European market as Chinese smartphone sale growth begins to slow down.

Cozza suggests that they could succeed if "they target the lower end and mid-to-lower end where…users are more open to switching brands."