[Koha] batch items modification: itemnumber contains space

Hi, I would like to use the batch items modification tool to a list of items, whose itemnumbers contain a space (e.g. 01 1234). The tool treats the two parts of the itemnumber as a distinct number (i.e. 01 and 1234), therefore no item is found. I tried enclosing the itemnumbers in inverted commas, and to escape the space, as well as several kinds of regex expressions for the space, but it does not work. Any hint? (All my itemnumbers are actually constructed in that way!) Many thanks, Giuseppe.