Draught coming through extractor fan from cooker hole in wall

The hole on the wall for the cooker extractor fan was badly created and over last few week with bad weather it feel like force 10 gale is blowing through the hole . There is space/gap between extractor fan casing and the hold in the wall so air is flowing in

Is there anything i can do to block the hole up

Would it be ok to use silicon or should i just stuff the hole with maybe

newspaper
Dry dishclothes
Insulation from attic

Suggestions

If the fitting is bad enough (say greater than 1/2") buy a can of expanding foam and slowly and carefully fill the hole.

You may also benefit from buying a anti backdraft device.

http://www.tlc-direct.co.uk/Products/BG4BS.html

http://www.askaboutmoney.com/showthread.php?t=93684