SVG: stretching an image

I'm playing around with the SVG tutorial and I simply loaded an image like this:

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">

<svg style="stroke-linejoin:round; stroke:black; stroke-width:0.5pt; text-anchor:middle; fill:none" xmlns="http://www.w3.org/2000/svg" font-family="Helvetica, Arial, FreeSans, Sans, sans, sans-serif" height="400px" width="400px" version="1.1" xmlns:xlink="http://www.w3.org/1999/xlink" viewBox="0 0 250 250">
    <rect y="0" x="0" height="250" width="250" stroke="black"  stroke-width="1" fill="blue" />
    <image y="0" x="0" height="250" width="250" xlink:href="http://www.blueprintmodel.co.uk/images/DSCF1438.jpg" />
</svg>

I get image in the center of viewBox, over "rect", even if height and width are same. My questions are:

How do I stretch an image to be size of rect?
Why "height" in "image" tag doesn't do the job?
Is there transformation like "stretch" or "resize" that I can use?(i couldn't find them)

Solution

Set preserveAspectRatio="none" on the SVG element:

<svg viewBox="0 0 500 500" preserveAspectRatio="none" xmlns="http://www.w3.org/2000/svg" >