"If you're able to crash something you are most likely able to exploit it," said Lukas Grunwald, an adviser to the German parliament on e-passports.

Grunwald first cloned the embedded chip in the e-passport last year, making it trivial to create a duplicate of an existing document.

Now he has delved further into the actual data stored on the chip, finding flaws in the way that the e-passports have been implemented.

He found that the passport photo was stored digitally in the industry-standard JPEG2000 format -- used in digital cameras and on websites -- making it easier to recycle old methods of attack.

By employing a technique known as 'buffer overrun', he injected rogue data into the passport photo file.

At a security conference, he scanned the e-passport through two different makes of scanner and crashed them both.

It also emerged that the fingerprints of the passport holder are stored as a standard image file.

This would be enough to allow someone to theoretically create fake fingerprints from gelatine that could be placed on the fingers and fool the scanner.

Such a technique has already been demonstrated by Japanese security researchers.