Sources told the Australian ABC network that Ben Zygier was arrested by the Mossad because they believed he gave a detailed account of Israel's activities to the Australian ASIO.
According to sources, Zygier met with ASIO a few times in Australia and during one of the meetings, rovided them with detailed accounts of a few Mossad operations, including the plans for a secret mission in Italy being planned for years. (Ynet)