Please, help me finding this movie title

First of all, I'm sorry for my bad english. I'm looking for a movie ('80s or earlier) in which a group of terrorists take over an airport. At the beginning of the movie the leader of the group is disguised as a priest but he meets a real priest. The real priest asks him where he is from and, unfortunately, he answers the same city the real priest is from, which starts to doubt him. The bad guy follow the real priest into the bathroom and kills him.