RCD trips on washing machine?

Hi my rcd keeps tripping on my washing machine. This only started yesterday, and it only happens once the water fills the drum to a certain level on all cycles. If i empty the water, and place ona spin, then it works fine, but once that water is just below door level it trips the whole flat.
I then have to manually remove the water witha jug before it will allow me to turn it back on. any ideas on how 2 fix this?

My flat is a new build just under 2 years old and have never had any probs like this before?

machine is a smeg WASHER DRIER - (never used the drier)

model number is WDI12 TYPE IS 22038

jason
December 2005