(Reuters) - Apple Inc Chief Executive Steve Jobs on Thursday sharply criticized Adobe Systems popular Flash multimedia software, calling it unreliable and ill-suited for mobile devices, escalating a pitched battle between the two companies.

Analysts said Jobs' pointed, nearly 1,700-word manifesto -- which Apple posted on its website -- helped push Adobe's shares down more than 1 percent, as it highlighted concerns about the future of Flash.

In an open letter entitled "Thoughts on Flash," Jobs laid out a laundry list of complaints about the technology, raising questions about its security, "technical drawbacks," and power-management. Click here to read the letter: here

"Flash is a successful business for Adobe, and we can understand why they want to push it beyond PCs," he said. "But the mobile era is about low power devices, touch interfaces and open web standards -- all areas where Flash falls short."

Jobs said Flash is "closed" because it is a proprietary system from Adobe, which controls everything from its features to its pricing. Similar charges are routinely lobbed at Apple's products and services, such as the App Store and iTunes.

Flash-based video and games are found on many Internet sites, but Apple has not allowed Flash on its iPhone and iPad.

"Adobe has characterized our decision as being primarily business driven -- they say we want to protect our App Store -- but in reality it is based on technology issues. Adobe claims that we are a closed system, and that Flash is open, but in fact the opposite is true," Jobs said.

Adobe declined to comment. But in an interview with the Wall Street Journal, Chief Executive Shantanu Narayen called the technology problems noted by Jobs "a smokescreen."

He also denied Flash is a closed platform and said Apple's restrictiveness makes it difficult for developers who create applications for multiple devices.

According to the Journal's website, Narayen labeled Jobs' letter an "extraordinary attack."

The hostility between Apple and Adobe has been brewing for months. Apple has criticized Flash as a buggy battery hog, while Adobe has accused Apple of exerting tyrannical control over developers creating programs for the iPhone and iPad.

The rhetoric has grown ever more heated. Earlier this month, Flash "platform evangelist" Lee Brimelow ended a blog post by saying, "Go screw yourself Apple."

Jefferies & Co analyst Ross MacMillan said the letter from Apple's CEO didn't raise any new criticisms about Flash, but simply put them on a very public pedestal.

"It's not positive in the sense that what Jobs is outlining is that Flash is in effect yesterday's technology and we shouldn't consider it as go-forward technology."

Jobs said he was concerned that allowing Flash-based applications on Apple's mobile devices would leave it "at the mercy" of a third party.

"We know from painful experience that letting a third party layer of software come between the platform and the developer ultimately results in sub-standard apps and hinders the enhancement and progress of the platform," he said.

Broadpoint AmTech analyst Brian Marshall said Apple clearly wanted to fire back to critics who have complained about the lack of Flash on its mobile devices.

And he said Apple also wanted to make clear that it doesn't plan to cede an inch of control on its fast-growing mobile platform, which now boasts more than 200,000 apps.

JOBS GOES PUBLIC AGAIN

Jobs has taken on an increasingly public role over the past few months, sitting down for magazine profiles and responding frequently to emails from Apple customers.

The enigmatic Apple CEO has a history of issuing public treatises on hot-button issues. In 2007, Jobs posted two such essays, "Thoughts on Music" -- where he urged for the abolition of the digital rights management system for music -- and "A Greener Apple," where he responded to criticism from environmental groups.

In his essay on Flash, Jobs said that while Apple's operating system for iPhone and iPad is proprietary, the company prefers open standards for the Web and favors technologies such HTML5 for creating multimedia programs.

Adobe has said 75 percent of all video on the web are Flash-based. Popular Flash-based sites such as Hulu can't run on the iPhone or iPad. But sites like YouTube have worked around this by specially designing non-Flash apps for those devices.

Jobs noted that outlets such as Netflix, ESPN, newspapers and TV networks have all designed offerings that can be played on its devices.

Shares of San Jose, California-based Adobe fell 1.4 percent to close at $34.96 on the Nasdaq. Shares of Cupertino, California-base Apple rose 2.7 percent to $268.64.

(Reporting by Gabriel Madway; additional reporting by Jim Christie; Editing by Bernard Orr)