Complex sentence: The "Irish Independent" reported that a call was made to Reuters, and that the call could not be authenticated but purportedly claimed revenge for the killing of an Islamic Jihad militant the previous Saturday as a motive.
Split into simpler sentences: The "Irish Independent" reported that a call was made to Reuters, and that the call could not be authenticated. It also said that the call had stated revenge for the killing of an Islamic Jihad militant the previous Saturday as a motive.