It is scheduled to hit U.S. market next weekend, followed by a wider international release at the end of the month.

The iPad proved more of a hit with consumers than analysts predicted, with sales of 15 million in its first nine months of release.

Jobs announced in January that he would take a third leave of absence to focus on his health.

In the last decade, Jobs has survived a rare but curable form of pancreatic cancer and undergone a liver transplant.

Chief Operating Officer Tim Cook has been running the company on a day-to-day basis.

In 2009, Jobs said in advance that he would take a six-month medical leave; this time, the company did not specify when he would return.