Is it possible to request Facebook permission `publish_actions` in app after login?

I'm implementing Facebook login with an extended permission publish_actions using PHP SDK. I added it in the scope parameter. It is no problem when user accepts it and allows to post to his/her timeline.

The problem comes when the user denies the permission while logging in. Then, the user connected to my app without publish_actions and he/she can't post to his/her timeline from my app. What if the user changed mind and he/she wants to post to Facebook from the app later?

Is it possible to request the permission in app, not from login URL, using PHP SDK?