Apple CEO and co-founder Steve jobs announced his resignation from the technology giant, saying he could "no longer meet the duties and expectations" of the job.

Chief operating officer Tim Cook, who has been acting as interim CEO, was immediately elevated to CEO, while Jobs will stay on as chairman of the board.

 "I have always said if there ever came a day when I could no longer meet my duties and expectations as Apple's CEO, I would be the first to let you know," Jobs said in a letter released by the company. "Unfortunately, that day has come."

 In recent years, Jobs has been struggling with health problems that forced him to take periodic leaves of absence from the company. In 2004, Jobs underwent successful surgery to treat pancreatic cancer and in 2009, he had a liver transplant operation.

Jobs’ departure from Apple was not completely unexpected since he went on medical leave for an undisclosed condition back on January 17th. Rarely seen this year, Jobs unveiled Apple's iPad 2 in March in San Francisco.

The Silicon Valley legend is known for his association with Apple's most successful innovations, including the Macintosh computer line, the iPod and the iPhone.