  We present a new approach to foreground removal for Cosmic Microwave
Background (CMB) maps. Rather than relying on prior knowledge about the
foreground components, we first extract the necessary information about them
directly from the microwave sky maps by taking differences of temperature maps
at different frequencies. These difference maps, which we refer to as internal
templates, consist only of linear combinations of galactic foregrounds and
noise, with no CMB component. We obtain the foreground cleaned maps by fitting
these internal templates to, and subsequently subtracting the appropriately
scaled contributions of them from, the CMB dominated channels. The fitting
operation is performed in wavelet space, making the analysis feasible at high
resolution with only a minor loss of precision. Applying this procedure to the
WMAP data, we obtain a power spectrum that matches the spectrum obtained by the
WMAP team at the signal dominated scales. Finally, we have revisited previous
claims about a north-south power asymmetry on large angular scales, and confirm
that these remain unchanged with this completely different approach to
foreground separation. This also holds when fitting the foreground contribution
independently to the northern and southern hemisphere indicating that the
asymmetry is unlikely to have its origin in different foreground properties of
the hemispheres. This conclusion is further strengthened by the lack of any
observed frequency dependence.
