Setting rounded corners for svg:image

Question

I was trying to make rounded corners for s svg:image (image embedded in SVG) with d3.js. I can't find out how to properly style the image, because according to W3C spec I should be able to use CSS, but neighter border nor rounded edges work for me.

Thanks in advance.

  vis.append("svg:image")
     .attr("width", width/3)
     .attr("height", height-10)
     .attr("y", 5)
     .attr("x", 5)      
     .attr("style", "border:1px solid black;border-radius: 15px;")
     .attr("xlink:href",
           "http://www.acuteaday.com/blog/wp-content/uploads/2011/03/koala-australia-big.jpg"); 

Edit:

Browsers tested: Firefox, Chrome