Paying off a mortgage

With the recent mini-collapse of the Euro it looks like a good time to pay off at least some of the outstanding mortgage. I though it would be reasonably easy as it was with my Uk mortgage but the French mortgage company requires a certificate to identify the origin of the funds. It is unclear as to what exactly they require. They mention 'attestation de votre banque(rachat de pret), attesttation de notariee etc. What exactly do they need to see? would a bank statement from my UK account or photocopy of my savings account be enoug ?

As usual with France everything is over-complicated and bureaucratic.