REAR HUB OIL LEAKS?

Hi i have a twin wheel LDV 400 van the rear hubs leak oil onto the drum via a leakoff hole, there ia a constant slow trickle on both hubs, i've put new seals in but the same happens after a few days, quite a bit drains out if stood for a long time, i dont want it to get onto the brakes, is there a simple way to stop it