phpinfo(): postgresql versions' mismatch

Dear all,

I have recently found out that  PHP libpq Version reported by
phpinfo() doesn't match the Actual PGSQL Version on the server.
I suspect this is the reason why some of postgresql queries do not run
via web interface and run without any problem via psql.
I have checked the web for an answer but found so far only this thread:
http://svr5.postgresql.org/pgsql-novice/2006-03/msg00208.php

They say that it is not critical if php uses the old libpq, still it
is better if the versions match.

The question is how what shall I do to make them match.

I'm using
Debian Sarge 3.1 (stable)
PostgreSql 8.1.4 (installed via Debian backports)
php version 5.2.0-8 (also installed from backports)
phpinfo() reports that:
    PostgreSQL(libpq) Version     7.4.7
    I believe I have both libpq3 and libpq4

I've checked /etc/php5/apache2/conf.d/pgsql.ini and
/etc/php5/apache2/conf.d/pdo_pgsql.ini

/etc/php5/apache2/conf.d/pgsql.ini:
    extension=pgsql.so
/etc/php5/apache2/conf.d/pdo_pgsql.ini:
    extension=pdo_pgsql.so

Thanks in advence for any advice,

Mihail