Apple Inc has reported a surprise fall in iPhone sales for the second quarter, indicating that customers had held back purchases in anticipation of the 10th-anniversary edition launch of the company's most important product.

Apple sold 50.76 million iPhones in its fiscal second quarter ended 1 April, down from 51.19 million a year earlier.

Analysts on average had estimated iPhone sales of 52.27 million, according to financial data and analytics firm FactSet.

However, revenue from the smartphones rose 1.2% in the quarter.

Expectations are building ahead of Apple's 10th-anniversary iPhone range later this year, with investors hoping that the launch would help bolster sales.

Apple typically launches its new iPhones in September.

Apple's 10th-anniversary iPhone range might sport features such as wireless charging, 3-D facial recognition and a curved display.

The company forecast total revenue of between $43.5 billion and $45.5 billion for the current quarter, while analysts on average were expecting $45.60 billion, according to Thomson Reuters I/B/E/S.

Analysts on average expect the company to sell 42.31 million iPhones in the current quarter, according to FactSet.

The company's net income rose to $11.03 billion, or $2.10 per share, in the second quarter, from $10.52 billion, or $1.90 per share, a year earlier.

Analysts on average had expected $2.02 per share, according to Thomson Reuters I/B/E/S.

Revenue rose 4.6% to $52.90 billion in the quarter, compared with analysts' average estimate of $53.02 billion.

Apple's revenue from the Greater China region fell 14.1% to $10.73 billion in the quarter, as cheaper rivals in the region chip away at sales.

A 17.5% jump in the company's services business, which includes the App Store, Apple Pay and iCloud, to $7.04 billion boosted revenue.

Shares of the world's most valuable listed company were down 1.2% at $145.78 in after-hours trading.

The company boosted its capital return programme by $50 billion, increasing its share repurchase authorisation by $35 billion and raising its quarterly dividend by 10.5%.