Log query statistics

Hi,

Im trying to disable query statistics from log, and I am unable to do it.
Cannot find the correct option. I have been cheking google, postgres
documentation, i didn't found how to do it so ... I am writting here:

I have my logs full of this info:

[...]
DETAIL: ! system usage stats:
! 0.001546 elapsed 0.001000 user 0.000000 system sec
! [0.097985 user 0.008998 sys total]
! 0/0 [0/0] filesystem blocks in/out
! 0/93 [0/3920] page faults/reclaims, 0 [0] swaps
! 0 [0] signals rcvd, 0/0 [0/0] messages rcvd/sent
! 0/0 [5/11] voluntary/involuntary context switches
! buffer usage stats:
! Shared blocks: 0 read, 0 written, buffer
hit rate = 100.00%
! Local blocks: 0 read, 0 written, buffer
hit rate = 0.00%
! Direct blocks: 0 read, 0 written
LOG: QUERY STATISTICS
DETAIL: ! system usage stats:
! 0.000610 elapsed 0.000999 user 0.000000 system sec
! [0.098984 user 0.008998 sys total]
! 0/0 [0/0] filesystem blocks in/out
! 0/22 [0/3942] page faults/reclaims, 0 [0] swaps
! 0 [0] signals rcvd, 0/0 [0/0] messages rcvd/sent
! 0/0 [5/12] voluntary/involuntary context switches
! buffer usage stats:
! Shared blocks: 0 read, 0 written, buffer
hit rate = 100.00%
! Local blocks: 0 read, 0 written, buffer
hit rate = 0.00%
! Direct blocks: 0 read, 0 written
LOG: QUERY STATISTICS
[...]

How to disable this output ? Im using postgres 8.2.4

Thanks in advance!
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