Wow, looks like this is hitting some raw nerves.
This is a very tricky situation but I don't think a blanket ban is necessary just some carefully considered laws/security precautions for example say a muslim lady in a burkha went into a bank to carry out something routine? perhaps a room to the side where she must reveal her face to confirm her identity? However, this would only work if there was cooperation with the muslim community.
I think thats the key, rather than bringing in a law/ban that just upsets a lot of muslims why not carefully negoiate with them or more appropriately a collection of imams. Muslims communities take all their direction from their imam much more so than christians do from a vicar/reverand almost to the point where if their imam says its "ok" its ok. So if you can get them to agree that a flash of the face under controlled coniditions in a public place is ok could solve a few problems.
I dare say that the more of an issue made of burkhas the more muslim women will wear them, esp the younger ones!
(I am a total leftie liberal, I know... I am prepared for the abuse )