Several online retailers have listed prices for the upcoming Xbox One and PlayStation 4, as the next generation of games consoles appear to cost significantly more than their predecessors.

Xbox One PS4 prices
The Xbox One is shown with the Kinect bar during it's unveiling in Redmond, Washington May 21, 2013. (Credit: Reuters)

UK-based retailer Zavvi was the first to include prices for the Xbox One and PS4, listing both at £399. However, Amazon UK and Amazon Germany are now both showing prices for the consoles.

Amazon Germany has both the Xbox One and PS4 listed at €599.99, (£513). Amazon's UK branch meanwhile lists both machines at the much higher price of £599.99, way above the £320 originally speculated by Microsoft analyst Paul Thurrott.

Prices have also appeared for Xbox One games. Amazon US is listing Watch Dogs, by Ubisoft at $99 (£65) while Amazon Germany has racing game Forza Motorsport 5 available for pre-order for €99. At the highest end of the game price spectrum, Amazon UK currently lists Call of Duty: Ghosts for £89.99. Games for next-generation consoles are expected to cost more than current generation games as the cost of development using new the technology will rise.

However, none of these prices have been confirmed by either Microsoft or Sony; a disclaimer alongside the Amazon listings reads: "There are no official prices announced for Xbox One products. The price stated above is a placeholder. With our Pre-order Price Guarantee, you can order now and if the price decreases between the time you place your order and the release date, you'll be charged the lowest price."

Though retailers are currently listing both the PlayStation 4 and Xbox One at the same price, it's likely that the PS4 will be cheaper than the Xbox. Though the hardware used by the two machines is similar, the Xbox One features a multitude of video streaming and social features that are likely to drive the price-tag up. It's intended to replace set-top boxes as a way for people to watching television and video in their living-rooms. As Enders analyst Heloise Thomson told IBTimes UK: "I think they're gunning for the Xbox to be a major product so they can start pushing their brand into a lot of new revenue streams."

Sony on the other hand is positioning the PlayStation 4 as a streamlined console, more dedicated to gaming. In a recent interview at the AllThingsDigital conferece, reported by Game Industry International, Sony President and CEO Kaz Hirai said: "The most important thing we need to make sure we do at least initially is that we all agree and understand that the PS4 is a great videogame console that appeals to video gamers...we take a look at this first and foremost as a game console."