Global PC sales rose 18 percent year-on-year for the third quarter of 2011, analyst firm Canalys has said.

Total sales of tablets were almost three times the level they were at in Q3 2010, with notebook sales up 9 percent. Desktop sales were also up 8 percent though netbook sales declined by 28 percent.

Canalys argues that although tablets continue to disrupt desktop, notebook and netbook sales, they are also the driving force in the growth of the PC market. China is the region where demand is highest, with 18 percent of worldwide volumes of PC sales, representing growth of 27 percent.

Apple’s tablet shipments grew by 166 percent though its share of the worldwide market fell from 96 percent in Q3 2010 to 67 percent in Q3 2011 as a result of increasing competition from rivals Samsung, Asus and Acer, Canalys said. It also predicted that Apple's market share would be further eroded next quarter.

Apple sold 11 million iPads in the last quarter and remains in second place in the total PC market with a 15 percent share, behind HP (16 percent) and ahead of Lenovo (12 percent), Dell (10 percent) and Acer (10 percent). Apple also maintained a top-two position in each region, Canalys said.

"Ongoing legal and media battles between Apple and its current closest competitor, Samsung, kept the top two pad vendors in the spotlight over the course of Q3," said Canalys analyst Tim Coulling.

"The result is that the pad market is being portrayed as very much a two-vendor race, with Samsung benefitting the most from the extra publicity on the global stage. In reality though, competition is intensifying as more vendors enter the market and seek to capitalize on growth opportunities."

However, the two-horse race scenario won't last for long, at least in the US. The launch of the Kindle Fire in the run-up to Christmas will see Amazon grab second place in the US tablet market, with sales of two million Kindle Fires expected in the fourth quarter.