How to set the .webpart file to load UserControl from physical path?

Question

In asp.net we can generate a webpart component by using WebPartManager.importWebPart(reader,err) function.

And the xml configuration file(.webpart file) likes:

<webParts>
<webPart xmlns="http://schemas.microsoft.com/WebPart/v3"&gt;
<metaData>
   <type src="~/webpart/wp.ascx"/>
</metaData>
...

In here, does the src parameter must be virtual path? Could I make the importWebPart function to load the UserControl file by physical path?

Thank you