Apple claimed a quarterly record for iPhone and iPad sales in the quarter to 28 December 2013, with Tim Cook, its CEO, stating it is “really happy” with the performance.

But the news failed to impress the market, with iPhone sales coming in below analysts’ guesses.

Coupled with muted revenue forecasts for the  coming quarter, there is concern that the company is entering a period of slowed growth.

Apple sold 51 million iPhones, compared with 47.8 million in the year-ago quarter. iPad sales of 26 million were up from 22.9 million year-on-year.

iPhone revenue was $32.5 billion, up 6 per cent from $30.7 billion year-on-year. iPad revenue was $11.5 billion, up 7 per cent from $10.7 billion.

Unsurprisingly, the company has not provided any detail on the split of iPhone sales between the iPhone 5s and iPhone 5c, amid speculation that the latter device is underperforming.

It was noted that there had been “supply constraints” on the iPhone 5s, which Cook said had led to issues in markets including North America, where “the mix was stronger to the iPhone 5s”.

In its home market, it was also noted that some operators had changed their upgrade policies, which had lengthened the time for customers to buy new devices.

iPhone sales growth in Japan were described as “very strong” year-on-year, following the addition of NTT Docomo to its operator roster alongside SoftBank and KDDI.

Cook also noted that following the long-anticipated launch of the iPhone by China Mobile, the company last week saw  “the best week for activations we’ve ever had in China”, and with the rollout of the operator’s 4G network in the coming year, “we’ve quite the ramp in front of us”.

iPad sales were described as being “very robust” in China, with sales more than doubling year-on-year. There was also strong iPad sales growth in the Middle East, Latin America, Russia and western Europe.

On a group level, the company posted a quarterly net profit of $13.1 billion, flat year-on-year, on revenue of $57.6 billion, up from $54.5 billion.

In its conference call, Peter Oppenheimer, SVP and CFO of Apple, said that “no single technology company has ever generated that much revenue in a single quarter”, noting that it was achieved despite “foreign exchange headwinds”, a year-on-year decline in iPod sales, and higher deferred revenue rates for iOS and Mac products.

For its fiscal second quarter, Apple is forecasting revenue of between $42 billion and $44 billion.