<?php
$arrItemList = array("IE,GB","BE,LU,GB","AU,NZ");
$callback = function('$warr,$v'){
$warr = array_merge($warr,$explode(",",$v);
return $warr;
}
$arrCountrylistToFilter = array_reduce($arrItemList["regions"],$callback);
print_r($arrCountrylistToFilter);
?>