SAN FRANCISCO - Apple has officially announced the iPad 2, which has a March 25 release date in Canada.

Apple CEO Steve Jobs briefly emerged from his medical leave and walked on stage to standing ovation Wednesday to unveil the second-generation of the popular iPad, which will go on sale March 11 in the U.S.

Jobs looked frail and wore his signature black mock turtleneck, blue jeans and wire-rimmed glasses.

"We've been working on this product for a while, and I just didn't want to miss today," Jobs said at the San Francisco event. "Thank you for having me."

The next-generation tablet computer has a faster processor than the original iPad's. As expected, it comes with two cameras for taking photos and video chatting. The battery life will be the same as the original -- about 10 hours of "on" time and a month on standby.

The iPad 2 is also thinner -- 8.8 millimetres instead of the current 13.4 millimetres.

"The new iPad 2 is actually thinner than your iPhone 4," Jobs said.

In the U.S., the new iPads will cost the same as the originals -- US$499 to $829, depending on storage space and whether or not they can connect to the Internet over a cellular network. In the U.S., the iPad 2 will work on AT&T Inc. and Verizon Wireless.

Jobs announced in January that he would take a third leave of absence to focus on his health. In the last decade, Jobs, 56, has survived a rare but curable form of pancreatic cancer and undergone a liver transplant.

Chief Operating Officer Tim Cook has been running day-to-day operations.

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. The last time Steve Jobs went on medical leave, marketing chief Phil Schiller was the main presenter at product launch events.