Israeli President Shimon Peres said on Tuesday that the threat of a nuclear-armed Iran was growing under the "terrifying dictatorship" ruling the Islamic republic.

"The Iranian danger has grown," Peres said at the opening of the newly-elected Israeli parliament. "It threatens our existence, the independence of the Arab states, the peace of the whole world," AFP reported.

"At its head stands a group of ayatollahs in their religious robes,  a terrifying dictatorship, staining Persian history and a nightmare for its people," he said.

Addressing the opening of the 19th knesset elected in a January 22 general election, Peres called on the United Nations and the Arab League to act urgently to end the turmoil in Syria.

"Iran is a danger and Syria is a tragedy. Its president butchers his people. In my opinion the UN should task the Arab League with the immediate formation of a transitional government in Syria to save it from self-destruction. Assad, who has murdered tens of thousands has also murdered his future," he said.