First, if you embed SVG as <img>, browsers won’t open links, as well as they wont run scripts inside <img>, because, well, you embed an image, and very probably your image may appear inside an <a>, and you can’t put links inside links.
And to make links open in new tabs, you can use either the target attribute, like in HTML, or xlink-specific xlink:show attribute with the value new. The SVG spec says the following:
[xlink:show] attribute is provided for backwards compatibility with SVG 1.1. It provides documentation to XLink-aware processors. In case of a conflict, the target attribute has priority, since it can express a wider range of values.
And the values of the target attribute can be:
- _replace
- _self
- _parent
- _top
- _blank
Thus, in your SVG you need to write as follows:
<a xlink:href="http://example.com" target="_blank">[...]</a>
But currently all browsers capable of showing SVG support both xlink:show and target attributes (I haven’t tested in IE9 though).