SAN FRANCISCO (MarketWatch) -- Apple Inc. Chief Executive Steve Jobs issued a rare public critique Thursday of products developed by Adobe Systems Inc., escalating the hostility between the two Silicon Valley icons.

In a nearly 1,700-word statement posted on Apple's AAPL, +1.50% main Web site and titled "Thoughts on Flash," Jobs -- known for dashing off terse emails -- starts off by noting that he has a long history with Adobe's ADBE, +0.22% founders, going back to "when they were in their proverbial garage."

Apple was "their first big customer," and it owned a large stake in Adobe for many years, he writes.

Apple CEO Steve Jobs penned a 1,700 word essay on why he won't allow Adobe's Flash technology to be used on the iPad and other Apple products. AllThingsD

But the Apple CEO then goes on to write that "since that golden era, the companies have grown apart." Adobe's Flash technology, which Apple has not blessed for use on its popular iPhone and iPad devices, represents "a closed system," Jobs writes, whereas Apple believes standards used to develop Web sites should be open.

Jobs' personal dislike for Adobe's Flash technology has been widely reported, though his feelings have largely been expressed in private. Read the full text of Steve Jobs' statement on Adobe and Flash here.

Last week, Adobe announced that, following years of effort, it would cease funding projects aimed at getting Flash onto the iPhone. See related story about Adobe's Flash decision for the iPhone.

At that time, Adobe complained that it was Apple that was building a closed system, by trying to "tie developers to its own platform." In contrast, Flash is developed to be used on "multiple platforms and devices." In the future, Adobe said, it would focus on developing Flash for devices running on Google Inc.'s GOOG, +0.01% open-source Android operating system.

An Adobe spokeswoman said in a statement that, "Apple's moves to block Flash and other technologies are designed to protect a business model that locks developers and consumers into a single, proprietary stack. Recent changes to Apple's licensing agreement are proof of that. Any attempt to position this solely as a technology issue is a smokescreen."

In a taped interview with Wall Street Journal Deputy Managing Editor Alan Murray, Adobe CEO Shantanu Narayen defended Flash, saying it benefits designers and publishers.

"It doesn't benefit Apple, and that's why you see this reaction" from Jobs, Narayen said.

In his posting, Jobs acknowledges that many Apple products are proprietary, such as the iPhone and iPad operating systems. But he seeks in the letter to distinguish between the need for such technologies to be open, and the need for open standards required to build Internet services and sites.

Adobe's Flash is used across much of the Internet to develop animation and video services. But Jobs writes that services that often rely on Flash, such as YouTube, are also available on Apple devices in "a more modern format."

In addition, Jobs said that there are stability concerns with Flash.

"Flash is the number one reason Macs crash," Jobs writes, referring to Apple's personal computers.

"We have been working with Adobe to fix these problems," Jobs writes, though he adds that Adobe's past announcements that Flash would be coming to "a smartphone" were premature, adding, "We think it will eventually ship, but we're glad we didn't hold our breath. Who knows how it will perform?"

Adobe developed its most recent iteration of Flash to be able to write applications initially for one device, but then have it reproduced for another. But Jobs writes that such an approach is flawed, because its results are often substandard.

"Flash is a successful business for Adobe, and we can understand why they want to push it beyond PCs," Jobs writes. "But the mobile era is about low power devices, touch interfaces and open Web standards."