Steve Jobs is to take medical leave from the company, the Apple CEO told colleagues in an email.
Jobs will take the time off to focus on his personal health. In 2008 he began a six-month absence at Apple to undergo and recover from a liver transplant, as part of a series of treatments arising from pancreatic cancer.
“At my request, the board of directors has granted me a medical leave of absence so I can focus on my health. I will continue as CEO and be involved in major strategic decisions for the company,” Jobs said in an e-mail.
"I have asked Tim Cook to be responsible for all of Apple's day to day operations,” the note added.
Apple shares have frozen due to the announcement being made on a public holiday in the US, where no trading occurs.