SAN FRANCISCO - Apple's new chief executive officer (CEO) Tim Cook on Thursday sent a company-wide email, assuring employees that the technology giant is going to be the same under his leadership as it was under Steve Jobs, US media reported.

Apple COO Tim Cook (L) and CEO Steve Jobs answer questions during a news conference on antenna problems with the iPhone 4 at Apple headquarters in Cupertino, California, in this July 16, 2010 file photo. Jobs has resigned his position as CEO of Apple, and recommended Cook as his replacement, the company announced August 24, 2011. [Photo/Agencies]

Apple on Wednesday announced that Jobs has resigned as the company's CEO and its board has named Cook as the replacement, raising new concerns about Apple's future development.

"I want you to be confident that Apple is not going to change. I cherish and celebrate Apple's unique principles and values. Steve built a company and culture that is unlike any other in the world and we are going to stay true to that - it is in our DNA," Cook wrote in the letter.

The letter was first published by technology news site Ars Technica and its authenticity has been verified by several news sources.

Cook, 50, once served in IBM and Compaq before he joined Apple in 1998. He was promoted to the chief operating officer in 2007 and has been de facto CEO responsible for most of Apple's day-to-day operations during Jobs' medical leaves.

Although Cook is different from the showman type that Jobs is, it is widely believed that he is the best and ideal candidate with whom Apple could use to replace the irreplaceable.

Analysts said the replacement will not affect Apple's business at least in short term, but it is unclear whether Apple's innovation and operational efficiencies will continue unabated.

Apple's Chief Operating Officer Tim Cook speaks during Verizon's iPhone 4 launch event in New York in this January 11, 2011 file photograph. Cook has been named Apple's new CEO after current CEO Steve Jobs resigned on August 24, 2011. [Photo/Agencies]