Shipments of portable web-connected tablet devices based on 'lite' operating systems, a market currently dominated by Apple's iPad, will hit 150 million per year in 2015 according to analyst firm Ovum.

Sales of such devices will grow from 14.2 million in 2010 at a compound annual growth rate of 60 per cent, the company said. However, the explosion in tablet sales will not impact the smartphone market.

Tony Cripps, Ovum principal analyst, said: "This huge growth in shipments will be dominated by tablet-style technologies such as the iPad and will mainly be driven by consumers buying devices to complement their smartphones. This will either be as a 'third device' where there is a high-penetration PCs or the primary computing device where there is low-penetration.

"Nonetheless, the greater ease of use of smartphones for the majority of consumers means that shipments of the tablet and other 'lite' OS devices will not dramatically erode the growing demand for smartphones. This is especially pertinent given their obvious similarity in hardware and software technology," Cripps continued.

Earlier this week, Macworld reported that the iPad dominated the media tablet in Q3 2010, according to figures from IDC. IDC's definition of a 'media tablet' fits very closely with what Ovum refers to as 'lite' tablets, running lightweight operating systems such as iOS or Android OS.

The news for the iPhone, though, isn't so good, according to Ovum. The firm believes that "Android will overtake the iPhone in mobile developers' affection by end of the year" and that Windows Phone 7 will be the fastest growing smartphone platform.

According to data from comScore , Android usage has already surpassed that of the iPhone in the US, as Macworld reported last week, though this could quickly change with the impending launch of the Verizon iPhone.

However, Apple will see little reason to worry about Ovum's predictions if its Q1 2011 results are anything to go by - the company reported record sales of iPhones, iPads and Macs.