VMware, the incumbent power in the blossoming realm of virtualization, has accused Microsoft of using foul play to promote its own competing products.

In a white paper published Friday, the EMC subsidiary said Microsoft is using Windows licensing terms to prevent customers from taking full advantage of virtualization.

"Microsoft is trying to restrict customers' flexibility and freedom to choose virtualization software by limiting who can run their software and how they can run it," VMware said.

The software giant rejected VMware's assertions.

"Microsoft believes the claims made in VMware's white paper contain several inaccuracies and misunderstandings of our current license and use policies, our support policy and our commitment to technology collaboration," Mike Neil, Microsoft's general manager of virtualization strategy, said in a statement Tuesday. "We believe that we are being progressive and fair with our existing licensing and use policies and creating a level playing field for partners and customers," he said

Neil added that he believes Microsoft and VMware will be able to settle their differences.