Microsoft has joined archrival Apple in criticizing Adobe Systems' widely used Flash multimedia software, creating a rare bond among the two computing giants.
Apple Chief Executive Steve Jobs has sharply criticised Flash, which is used to produce videos and games for many internet sites. Apple has banned Flash from its iPhone and iPad.
A Microsoft executive pitched in later that day, saying while the ubiquity of Flash makes it easy for consumers to access video on the web, the standard has flaws.
"Flash does have some issues, particularly around reliability, security and performance," said Dean Hachamovitch, general manager for the internet Explorer browser.
He said that Microsoft is backing the same protocols for delivering multimedia content over the web that Apple is promoting, a group of standards known as HTML5.
But Microsoft was more conciliatory toward Adobe than Apple, saying it works closely with Flash engineers to help fix bugs that it finds in the product.
Steve Jobs, by comparison, said in his open letter that it is time for the industry to move beyond Flash.
"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."
Meanwhile Adobe dismissed the claims, saying that Apple was simply trying to promote its own products.
"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," Adobe spokeswoman Holly Campbell said.
Some 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, according to Adobe. But sites like YouTube have worked around this by specially designing non-Flash apps for those devices.