Apple CEO Steve Jobs is taking time off from work to concentrate on his health.

During his absence, Chief Operating Officer Tom Cook will be responsible for day to day operations.

Jobs will stay on as CEO and will be involved in major strategic decisions for the company.

It's not known for how long he will be on leave.

Jobs has been the face of Apple for years, being in front of the camera for some of the firm's major launches such as the iPhone and iPad.

In a letter sent round to all Apple employees he said: "I love Apple so much and hope to be back as soon as I can. In the meantime, my family and I would deeply appreciate respect for our privacy."

Jobs was first diagnosed as suffering from pancreatic cancer in 2004 and had a tumour removed.

He took a leave of absence from Apple in late 2008 for a liver transplant.