Microsoft is placing "troublesome" restrictions on hardware makers working on Windows 8 tablets, according to both Acer's president and its CEO.

Speaking yesterday at the Computex trade show in Taiwan, Acer President Jim Wong said Microsoft had chosen five chip manufacturers--Intel, Advanced Micro Devices, Nvidia, Qualcomm, and Texas Instruments--to provide processors for the next generation of Windows tablets, according to The Wall Street Journal. Taking it a step further, Microsoft then decided to limit each chipmaker to supplying chips to no more than two hardware makers, a move that Wong sees as restrictive.

"The industry does not belong to Microsoft and it does not belong to Intel," Wong said, according to the Journal. "It belongs to all participants. They cannot make the decision for all of us. That is the problem."

According to Bloomberg, Acer CEO J.T. Wang also chimed in at Computex with comments critical of Microsoft's stance on Windows tablet makers. Microsoft is "really controlling the whole thing, the whole process," he said, and chipmakers and PC manufacturers "all feel it's very troublesome."

In response to CNET's request for comment, a Microsoft representative sent the following statement: "We're still in the development process on the next version of Windows. We are continuing the engineering work with our silicon partners as part of the technology preview we talked about in January, and continue to talk regularly with hardware partners around the world as part of our development process."

Microsoft will reportedly unveil and demo its new tablet-based operating system sometime this week, possibly at the All Things Digital D9 conference in California. Steven Sinofsky, president of Microsoft's Windows division, is scheduled to speak at D9 later today.

The company had already announced at CES in January that it is prepping a version of Windows 8 to run on ARM-based devices, such as smartphones and tablets. But the company has been cagey about revealing too much about its next-generation operating system.

CEO Steve Ballmer said last week that Microsoft will launch Windows 8 in 2012, though his comments were quickly shot down as a "misstatement" by his own company. The week before, Intel Senior VP Renee James said that Microsoft plans to launch multiple versions of Windows 8 designed for both Intel x86-based PCs and ARM devices, but Microsoft blasted those comments as "factually inaccurate and unfortunately misleading."

Updated at 8:40 a.m. PT with a statement from Microsoft.