Smartphones using the Android platform boosted their US market share in recent months, extending their lead over Apple's iPhone, a new survey shows.

Android, the free mobile operating system from Google, accounted for 51.2 percent of US smartphone sales in the three-month period ending in February, said the survey from Kantar Worldpanel ComTech.

Android added 5.9 percentage points from a year earlier, while Apple's share fell 3.5 points to 43.5 percent.

Windows Phone, boosted by the new operating system introduced last year from Microsoft, increased its share to 4.1 percent, according to the survey released Monday.

BlackBerry,, which introduced a new smartphone platform in late January but started selling its new phones in the US market only in late March, saw its market share tumbled to just 0.7 percent, the report showed.

Verizon was the top carrier with 35 percent of smartphones sold in the period, followed by AT&T (26.7 percent) and Sprint (15 percent).

Kantar analyst Mary-Ann Parlato said Samsung, the largest Android smartphone maker, has been continuing to rise, particularly among Sprint customers.

"Of those who changed their phone over the last year to a Samsung smartphone, 19 percent had previously owned a Samsung featurephone, 15 percent owned a HTC smartphone, 14 percent owned an LG featurephone, 10 percent owned a Samsung smartphone and nine percent owned a BlackBerry," she said.

"It's apparent that Samsung is successful at capturing users from across the competitor set and not just gaining from their own loyalists."