Online retailer Amazon has launched a new tablet computer to rival Apple's best-selling iPad.

Two versions of the machine, the Kindle Fire and Kindle Fire HD, were unveiled at a press conference in the United States.

UK consumers will be able to buy the HD version, which has a seven-inch screen and was previously only sold in the US, for £159, while the second model is priced at £129.

The HD version has an 11-hour battery life, a camera and 16 gigabytes of storage and will have easy access to Amazon's Kindle book service and the streaming service LOVEFiLM, which is a subsidiary of the firm.

Amazon founder Jeff Bezos said: "Not only does Kindle Fire HD feature the most advanced hardware, it's also a service. When combined with our enormous content ecosystem, unmatched cross-platform inter-operability, and standard-setting customer service, we hope people will agree that Kindle Fire HD is the best seven-inch tablet available anywhere, at any price."

He also announced a new, smaller version of the Kindle e-reader, which will sell for £69.

The battle for supremacy in the technology marketplace is hotting up. This week also saw Finnish phone firm Nokia reveal details of two new phones that will run on Microsoft's Windows operating system, and next week Apple is due to hold a "special event" – widely believed to be the launch of its iPhone 5.