iSuppli has made an about turn on its previous claims that the iPhone was July's biggest-selling smartphone with 1.8 per cent of the US market.

The researchers insist that the device was the biggest-selling model in the consumer retail market, but issued a clarification to clients last night in which it pointed out that BlackBerry sales actually surpassed those of the iPhone, when corporate and enterprise sales are taken into account.

"iSuppli’s sell-through research and the subsequent press release indicated that the iPhone outsold all smart phone models in July in the United States on an individual basis," the analysts said.

"While iSuppli stands by this analysis, it is important to note that iPhone’s retail sales did not exceed the combined retail sales of the entire BlackBerry line of smart phones in the United States in July," the clarification adds.

Combining sales of all BlackBerry models in July reveals "approximately twice as many sales as the iPhone," iSuppli added.

Apple Insider adds new research from Piper Jaffray analyst Gene Munster, who believes Apple's recent decision to cut the cost of the iPhone has tripled sales of the device. The company is currently selling 27,000 units each day.

This means September's Apple iPhone sales could surpass those of the BlackBerry in the US this month, the report observes.