I have recently watched this presentation held by John Mearsheimer, professor of Political Science at the University of Chicago and he argues that political leaders lie way more frequent to their own people than lying in the international relations (minute 30).
This seems to make sense since in the international relations one expects the other part to distrust you more than your own people, so it is more difficult to lie. I am interested if there is at least one study to back this up.
I will tag this with the US tag to narrow down the scope of the question. However, I would also accept answer involving Europe.