number of interval expression matches as argument

Hi,

is there a way to pass the number of matches for an interval
expression as argument to to a function like this?

function foo (string, num) {
      sub(/([A-Z]* *){num}/,"",string)
      return string
}

bar="this is my string"
bla=for(bar, 2)

I'm using GNU Awk 3.1.5 and the  --re-interval switch, but I can not
get $num expanded to "2", I tried num and $num but it looks like I'm
to numb.

Kind Regards
Sirko