Amazon just dropped the price of its Kindle Fire HD e-reader tablet, offering the 7-inch slate with a 15 percent discount in the U.S. and UK.

With the new price cuts, the Kindle Fire HD now costs £139 (£20 off) in the UK and $169 in the U.S. ($30 off). Both prices are for the 16GB model.

Amazon's move to slash the prices of its 7-inch Kindle Fire HD likely comes as a response to Barnes & Noble's (B&N) recent price cuts for the NOOK HD, which see the tablet at £129/$149 for the 16GB model. MoDaCo founder Paul O'Brien was the first to spot the Kindle Fire HD promotion.

Both Barnes & Noble and Amazon list their price cuts as a "limited time offer." Considering the cut-throat competition between the two companies, it will be interesting to see which one will end the promotion first.

Amazon wanted to stay competitive and match B&N's price cuts with an attractive promotion of its own, but the NOOK HD is still cheaper even after Amazon's new price cuts. The motivation behind these discounts, however, is not the same for both firms.

Barnes & Noble is cutting prices in order to clear its stock of existing NOOK HD and NOOK HD+ models, as the company plans to license the brand to third-party manufacturers from now on. Amazon, meanwhile, seems to aim only to stay competitive.

Instead of making its own tablets, Barnes & Noble plans to focus on developing e-readers such as the SimpleTouch, based on e-paper technology. The company faced sluggish NOOK sales in the second quarter. Despite its e-reader hardware, software and accessories, B&N still lost 34 percent. The company blamed fading hardware appeal and a shortage of high-profile titles.

Amazon, on the other hand, seems to use Kindle discounts as a means to add further pressure on its archrival. This, however, should not come as much of a surprise, and it's not something new. When Barnes & Noble launched its NOOK back in 2009, Amazon immediately moved to cut prices for the second-generation Kindle in order to stay competitive.

The good news is that such fierce competition ultimately benefits the user. While the two companies are busy coming up with offers and counteroffers, consumers can take advantage of the price cuts and purchase their desired tablet for less than they normally would. Interested buyers in the U.S. can find the discounted Kindle Fire HD at this link, while UK customers can find it here.