Replace leading zero 0 with blanks using sed

Input file:

$ cat thres.txt
0002345
01234
0901234
0000034
14
000923

Required: Remove the leading zero's with blanks from the above file.

The sed solution:

$ sed -e 's/^0/ /;: loop' -e 's/ 0/  /;t loop' thres.txt

Output:

  2345
1234
901234
    34
14
  923