SAN FRANCISCO (AFP) - Apple's announced on Tuesday that its highly anticipated Apple Watch wearable devices unveiled last year are on track to begin shipping in April.

"We'd like to thank our customers for an incredible quarter which saw demand for Apple products soar to an all-time high," said chief executive Tim Cook.

The California-based tech giant's quarterly profit soared to a rtecord US$18 billion (S$24.1 billion) on the back of booming iPhone sales, especially in China.

Apple posted record revenue of US$74.6 billion in the quarter, during which 74.5 million iPhones were sold.

In the same three-month period at the end of 2013, Apple reported profit of US$13.1 billion on US$57.6 billion in revenue.

Analysts credited freshly released larger screen iPhone 6 models along with a partnership with China Mobile as powering sales.

Sales of iPhones doubled in Greater China, its number two smartphone market, according to chief financial officer Luca Maestri.

iPhone sales leapt 44 per cent in the United States and doubled in Brazil.

About 65 per cent of Apple's overall revenue came from sales outside the United States.

Sales of iPads dipped but Apple set new records in the quarter for sales of Macintosh computers and revenue from digital goods bought from its Apple Store.

The iPhone 6 was the most popular Apple smartphone during the quarter, but the 'phablet' style iPhone 6 Plus also "did incredibly well", Mr Cook said.

Apple's board of directors declared a cash dividend of 47 cents per share to be paid on Feb 12.

Apple shares rose nearly 5 per cent to US$114.25 in after-market trades that followed release of the earnings figures.