Jewish Spy

Can a Jew be a spy in a foreign society (for example in an Arab country) if it requires living life as a non-Jew and violating many commandments? Do the benefits of helping to protect Jewish lives outweigh the prohibitions?

There is a story in the Talmud of a Jew who who conducted himself as a non Jew so that he was able to listen to the plans and decrees of the government against the Jews, and even thwart them. In the story, Eliyahu himself declares the man to merit a great portion in the coming world.