PHP Startup: Unable to load dynamic library 'pdo-sqlite.so'

I found these issues after installing php5-sqlite :

PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php5/20131226/pdo_sqlite.so' - /usr/lib/php5/20131226/pdo_sqlite.so: undefined symbol: sqlite3_column_table_name in Unknown on line 0

PHP Warning: PHP Startup: Unable to load dynamic library '/usr/lib/php5/20131226/sqlite3.so' - /usr/lib/php5/20131226/sqlite3.so: undefined symbol: sqlite3_enable_load_extension in Unknown on line 0

p.s : so files exist

Details :

1. OS : Ubuntu 14.04 LTS
2. PHP : PHP 5.6.15

I have tried uninstalling (purge) and reinstalling PHP but the issues still remain.

I have tried commenting out extension=pdo-sqlite.so in /etc/php5/cli/conf.d/pdo_sqlite.ini, but it says "Driver not found".

Please help...