Amazon has launched three new versions of the Kindle Fire as it attempts to take a bigger chunk of the booming tablet market.
The world's biggest internet retailer unveiled the Kindle Fire HD in two screen sizes, 7in (17.8cm) or 8.9in (22.6cm).
An upgraded version of the existing device was also launched. It will cost £129, while the 7in HD tablet will have a £159 price tag.
The new machines come with advertisements known as "special offers" that appear when screens are locked and in the corner of the home screen, helping Amazon keep prices low.
The firm hopes the launch will enable it to compete with the more expensive Apple iPad, the best-selling tablet globally.
Amazon's expanding line-up also intensifies a battle with Google and Microsoft, who have both entered their own products into the tablet market.
The 8.9in HD device works off either Wi-Fi or fourth-generation wireless broadband, known as 4G.
Forrester Research analyst James McQuivey said: "Their first Kindle Fire tablet was a device that said, 'See, we can tie all this together,' but it wasn't a strong enough device.
"Now they've really come ready to show that their device line-up is going to be as good as their service line-up.
"They're tying those two things together, and at a price that is very, very hard to compete with. It's going to push everybody else's price buttons - including Apple's."
The premium Kindle Fire HD has a 1920-by-1200 resolution screen, lagging behind Apple's so-called 'retina' display. It is also slightly smaller than the iPad's screen.
Scott Tilghman, an analyst at Caris & Company, said: "Amazon is able to sell these products at or close to cost, while Apple has 40 to 50% gross profit margins and has always been very cautious with their product margins."
