All these rumours are pure bullshit. I have worked and stayed in Israel and have never come across Israeli National Bank. Listed below are some of the more reputable banks in Israel:-
a. Bank Leumi
b. Israel Discount Bank
c. Bank Hapoalim
There are some other smaller banks but I'm sure that there is no such bank called ISRAELI NATIONAL BANK.
I may not like Mahathir's style of talking and his arrogance. But I think his opponents are desparate to get back at him with all kind of accusations.