Sony claims that the PlayStation 4 has sold more than 20 million units to date, retaking the the top position in the U.S. market. The PS4 was the top-selling console and the leader in software sales in the U.S. in May, Sony Computer Entertainment (SCE) said.

The statement follows last month's announcement by rival Microsoft that its Xbox One video game device was the top seller in April.

Mike Nichols, corporate vice president for Xbox marketing at Microsoft, said in a statement that sales of Xbox One consoles in the U.S. were up 81 percent in May compared to the same month in 2014.

The news comes just days before the opening of E3 in Los Angeles, where Microsoft, Sony, Nintendo and third-party developers will show off their latest and greatest games and hardware. Microsoft unveiled a new version of the Xbox One on Thursday that sports a 1TB hard drive and costs US$400.

Microsoft has also announced a partnership with Facebook's Oculus to link the Oculus VR headset to Windows 10 devices and the Xbox One. The headset, set for launch to consumers next year, will be bundled with an Xbox One controller. Oculus VR users will be able to stream games to the Rift from their Xbox One using a Windows 10 PC.

Sony is also looking at the virtual reality market with the Project Morpheus headset, which requires the PS4 to function.