Why does PHP sqlite_libversion() function fail on Red Hat Enterprise Linux 6?

Issue

• Why does PHP sqlite_libversion() function fail on Red Hat Enterprise Linux 6?
• The message on RHEL seems to indicate that SQLite3 is loaded. but the PHP library does not seem to be able to connect.
• sqlite_libversion() fails to returns the version of the linked SQLite3 library.

# php -m | grep sqlite3
sqlite3

# cat /path2file/sqlite_libversion.php
<?PHP
echo sqlite_libversion();
?>

# php  /path2file/sqlite_libversion.php
PHP Fatal error:  Call to undefined function sqlite_libversion() in /path2file/sqlite_libversion.php on line 2