painting over rust stains

[J.JJ]

i have rust stains on the masonary paint on an external wall of my house from an old burglar alarm box, which has now been removed.
will a few coats of masonary paint kill off this staining or will it permeate through.
i have thought about painting over the staining with oil based undercoat and finishing off with masonary paint, but i am a little worried that this might peel due to the weather.

any thoughts would be helpful.

[ianmunt]

I'd give it a thorough cleaning down,check to see if you can see any metal in the wall are,a nail etc.If so remove and make good.If not a coat or two of aluminium primer.When thoroughly dry apply you masonary finish.Being water based,it will keep coming through masonary paint if you don't seal it fisrt