When redirect_uri is provided in getLoginUrl for facebook login integration, the fb_appid_access_token session is not visible. For some reason the fb_appid_access_token session is not set or may be destroyed. But when i don't provide redirect_uri, the fb_appid_access_token is getting set and i am able to view it by using print_r($_SESSION). Below is the code which i am using.
$loginUrl = $this->facebook->getLoginUrl(array("scope"=>"email,publish_actions","redirect_uri"=>"absolute url"));
P.S Codeigniter framework and facebook-php-sdk are used