The newly-unveiled 4G-capable 8.9-inch Kindle Fire HD tablet from Amazon is now available for pre-orders, though the online retail giant is yet to get the Federal Communications Commission (FCC)'s approval for selling the high-end tablet.

The approval of the FCC is mandatory for wireless communications devices as it underscores the assurance that the devices will operate safely and will not cause any inappropriate interference with other signals.

That the FCC has not yet approved the Kindle Fire HD 8.9 for sale is evident from a pre-order confirmation email which Amazon sent late Thursday for the $499-priced tablet that will seemingly challenge the popular Apple iPad.

The pre-order confirmation email sent to the potential buyers of the Kindle Fire HD 8.9 included a note which read thus: "We will send you an email asking you to confirm your pre-order of Kindle Fire when it is approved for sale by the Federal Communications Commission."

With Amazon having already announced that it intends shipping the Kindle Fire HD 8.9 on November 20, a spokesman of the company revealed that the device will probably receive due approval from the FCC before the shipments begin.

Nonetheless, with analysts noting that it is rather unusual for a company to announce its major new product without first getting the FCC approval, John Jackson - CCS Insight's wireless analyst - said: "I can't think of an instance where a device has been offered by a U. S. carrier or an independent retailer that has not had FCC approval yet."