Opposition leader Yitzhak Herzog (Zionist Union) has been identified as the second political leader under investigation for corruption.
Herzog is suspect of accepting illegal donations while running for the leadership of the Labor party in 2013.
He has responded to the reports by stating, "I welcome the investigation that is being carried out according to the Attorney General's statement. This is an attempt to politically vilify me that the Likud and frustrated activists tried before the elections and was disproven even then.
"I am confident that the investigation will disprove these delusional claims once and for all. I will cooperate completely with any who ask me in order to clear up the issue as quickly as possible."
Earlier Wednesday it was revealed that Shas head and Interior Minister Aryeh Deri is also being investigated.