Htaccess -> php code

Dear Everybody!

We are stuck with LDAP authentication...googled lot of forums, read lot of articles, without success.
May somebody knows the solution..

So, first, we have a working solution thru apache htaccess as a start

----
AuthType Basic
AuthName "xxxxxx"
AuthLDAPURL "ldaps:yyyyy:636/o=zzz?uid"
AuthLDAPBindDN "uid=apptttttt,o=ooooooo,o=rrrr,o=sssss,o=ppp"
AuthLDAPBindPassword "hhhhhh"
AuthzLDAPAuthoritative off
AuthBasicProvider ldap


#ADMIN (admin group)
require ldap-group cn=App_numbernumbernumber,ou=App-servergroups,o=ff,o=Groups,o=zzz

----

that htaccess succcesfuly checks an user belongs to a group and authenticates him.

However, we would like to convert it to PHP, but it fails every time.

General, the question is, how could we check directly when somebody is a member of a specific ldap group - above is "cn=App_numbernumbernumber"
(whitout requesting his group memberships from ldap)

Thanks in foreword,

David