Supplies of Apple's Thunderbolt Display are dwindling, hinting that a 4K update of the product could be on the way.

During its WWDC 2013 keynote on 10 June, Apple treated us to a sneak peek of the new Mac Pro, which is set to hit the shelves later this year. While showing off the new Mac Pro, Apple highlighted that it will be able to support multiple 4K displays, which suggests that the company may be working on a new 4K Thunderbolt Display ready to launch alongside the new professional Mac.

See: Mac Pro 'Astounding', MacBook Air 'Awesome' – WWDC developers react

Reports that several third-party retailers are running low on stock of Apple's Thunderbolt Display have added to the speculation that a 4K model could be coming. The Thunderbolt Display has not been updated since Apple debuted the product in 2011.

MacTrast reports that several Apple resellers in the US are warning that they have five or less units, and on some occasions zero, of the Thunderbolt Display in stock, while one reseller, Adorama, states that the products is "no longer available".

Further still, MacTrast claims to have spoken someone from Adorama's customer support, who revealed that "the manufacturer is no longer allowing us to order new inventory for this item, and it has been removed from our system." Additionally, a spokesperson from MicroCenter told MacTrast the reseller was also unable to order more units of Apple's Thunderbolt Displays.

The Thunderbolt Display's current resolution is 2560 x 1440 pixels, but a 4K update could bring the resolution up to the ultra high definition (UHD) standard of 3840 x 2160 pixels.

Another hint comes directly from Apple itself. Despite the lack of a Retina display on any of Apple's desktop products, the company has posted a high-resolution OS X Mavericks wallpaper to its website, with a resolution exactly double that of the current Thunderbolt Display and 27in iMac, at 5,120 x 2,880 pixels. This means that a Retina iMac could be on the cards too.

It's been speculated that, as well as the 4K upgrade, the new Thunderbolt Display could sport a new, slimmer design, reminiscent of the new iMac's design.

See also:

New Mac Pro reaction: Video pros speak about GPU and storage concerns

Intel makes Thunderbolt 2 official, offers 4K video transfer and display at 20Gbps

iTV rumours: Apple's 4K Ultra HD television set to arrive late 2013 or early 2014

MacBook Pro with Retina Display (2013) review