Kindle gets longer battery life and PDF reader

Amazon has updated its Kindle e-book reader to significantly extend the battery life and add a native PDF reader.

Available now, the updated reader offers a battery life of up to seven days even with wireless turned on, Amazon said, compared with the current four days.

Meanwhile, a new PDF reader tool enables Kindle users to view documents in Adobe's popular PDF format without conversion by emailing the files to their Kindle email address or copying them over using a USB connection.

The improvements come in a new version of the Kindle firmware, and Amazon said that previous purchasers of the new Kindle will also be able to receive this via a firmware update automatically delivered via the device's wireless network.

"Kindle, already the number one bestselling, most wished for, and most gifted product on all of Amazon.com, is now even better, with 85 per cent more battery life and a built-in PDF reader," said Amazon vice president Ian Freed.

Amazon has offered an international version of the Kindle since October, which uses a 3G mobile network to allow customers to purchase and download new e-books.

However, the device still has to be purchased in dollars and is effectively imported from the US. It also ships with a US mains adapter.