Apple lost more than $50bn (£31.8bn) of its market value last week after shares slumped 12% because of weaker-than-expected iPhone sales at Christmas, reinforcing fears that the retailer and technology giant is losing its dominance in smartphones.

Apple posted first-quarter group revenue of $54.5bn (£34.66bn), compared with $46.3bn (£29.44bn) in the same period last year. Sales at retail stores rose 5% to $6.4bn (£4.07bn).

Apple sold 47.8 million iPhones in the quarter, bolstered by the iPhone 5 release.

It sold 22.9 million iPads, up from 15.4 million, on the back of the new iPad and iPad mini launches.