Google's Nexus 7 tablet proved to be a smashing hit, and the company seems to have sold out of the higher capacity model in both the UK and the U.S., at least on its own Google Play site. As of the weekend, the 16GB version of the recently launched Nexus 7 was no longer in stock. "16GB coming soon - leave email for notification," reads the page. Meanwhile, the 8GB version is still in stock on the Google Play store.

Sources close to Google told The Guardian that "the search giant seriously underestimated the demand for the 16GB version of its Nexus 7 tablet," which enjoyed much higher demand compared to the cheaper, 8GB model. The 16GB version costs more, but it proved more popular because the tablet does not include a microSD card slot, which means its storage is not expandable. Demand for the smaller capacity version remains comparatively low.

Faced with overwhelming demand, Google has now halted further orders of the 16GB Nexus 7 on its Google Play store in the United States and the UK. People who ordered the tablet in the period up to the end of last week will have their order fulfilled, but the current shortage of stock means a pause in sales.

Meanwhile, the 8GB model is listed as "in stock" and promises delivery within 3-5 business days. This smaller capacity version of the Nexus 7 is available exclusively through Google's own store. According to The Guardian, the search giant has deliberately stocked its Google Play Store with more units of the 8GB model as part of a strategy to lure buyers into committing to the company's "cloud" concept.

As the tablet does not offer the possibility to expand storage with a microSD card, users opting for the cheaper version are seen as more likely to make use of Google's cloud-based storage service. On the other hand, the Nexus 7 is Wi-Fi only, which means it's rather difficult to have continuous connectivity on the move.

"The Guardian understands that Google's planners had thought that buyers on the Google Plat Store, more than from physical or online retailers, would be more committed to the company's 'cloud' concept, and so would have more of their content stored online, rather than wanting to keep it on the device," wrote the publication. "But most buyers appear to have noted that the storage on the device cannot be upgraded and decided to get the larger model."

Google has already postponed the delivery date for the 16GB model once, putting it off by up to a week. Asus is expected to ramp up production of another batch of the larger-capacity Nexus 7, but that could take several weeks to arrive.

The Nexus 7, made in collaboration with Asus, marks Google's first foray into the increasingly more competitive tablet market. The huge popularity of Google's new tablet has even sparked rumors that Apple, which currently dominates the tablet market, will launch an iPad Mini to better compete with rivals. Apple, however, has not confirmed such plans.