Apple has reported a 30% rise in quarterly profits to $11.1bn (£7.3bn), with the sale of 48 million iPhones being credited.

The tech firm, which is increasingly relying on healthy iPhone sales to drive profits, said its figures contained only two days of sales for its latest models - the 6S and 6S Plus - which became available last month .

As a result, Apple said it expected to beat last year's record of 74.5 million iPhones sold in the Christmas holiday quarter.

The forecast helped its share price rise more than 2% in after-hours trading - a performance that was matched when trading began on Wednesday.

Apple shrugged off fears that the economic slowdown in China and other emerging markets would soon feed into its sales.

It said revenue almost doubled in China, Hong Kong and Taiwan during the last quarter of its financial year, which ran to 26 September, compared to the same period a year ago.

Commenting on its annual performance, chief executive Tim Cook said: "Fiscal 2015 was Apple’s most successful year ever, with revenue growing 28% to nearly $234bn.

"This continued success is the result of our commitment to making the best, most innovative products on earth, and it’s a testament to the tremendous execution by our teams.

"We are heading into the holidays with our strongest product lineup yet, including iPhone 6s and iPhone 6s Plus, Apple Watch with an expanded lineup of cases and bands, the new iPad Pro and the all-new Apple TV which begins shipping this week."

Apple remains the world's biggest company by market value despite its share price remaining about 15% off the highs it achieved during the summer.

The reduction has been partly put down to fears about falling demand, particularly in Asia, for iPhones.

Apple said its Watch contributed to the revenue growth in the fourth quarter, though it did not provide a breakdown of sales figures.

It pointed to revenues of just over $3bn from Apple TV, Apple Watch, Beats products, iPod and Apple-branded and third-party accessories.

iPad sales were down by more than one million - to 9.9 million - on the previous quarter.