Vienna ? The head of the U.N. atomic watchdog is asking for international input on how to persuade Israel to join the Nonproliferation Treaty, in a move that is sure to add to pressure on the Jewish state to disclose its unacknowledged nuclear arsenal.

In a letter made available Wednesday, Yukiya Amano asked foreign ministers of the International Atomic Energy Agency’s 151 member states to share views on how to implement a resolution demanding that Israel “accede to the” Nonproliferation Treaty and throw its nuclear facilities open to IAEA oversight.

The letter was shared with The Associated Press amid renewed Arab criticism of Israel during an international conference at U.N. headquarters in New York. Islamic nations used the second day of the nonproliferation meeting Tuesday to call for a nuclear-free Middle East, while criticizing Israel for not divulging its nuclear capabilities and refusing to sign the nonproliferation treaty.