del operator and global namespace

[alust]

Hello,

Can somebody explain this strange (to me) effect please.

In this program it is impossible to access a global variable within a
function:

$ cat /tmp/test.py
x='xxx'
def f():
     print x
     del x

f()

$ python /tmp/test.py
Traceback (most recent call last):
   File "/tmp/test.py", line 6, in <module>
     f()
   File "/tmp/test.py", line 3, in f
     print x
UnboundLocalError: local variable 'x' referenced before assignment

But if we comment the del operator the program will work:

$ cat /tmp/test.py
x='xxx'
def f():
     print x
     #del x

f()

$ python /tmp/test.py
xxx

So why in this example the print operator is influenced by del
operator
that should be executed after it?

--
Thanks, Alexei