Israeli President Shimon Peres said on Tuesday that Israel's longstanding refusal to confirm or deny reports that it has a nuclear arsenal is itself an effective deterrent.

"Israel has 'real or assumed' capabilities that are sufficient for deterrence," Peres's office quoted him as telling a closed-door annual meeting of Israel's envoys abroad.

"None of us know what there really is in Dimona," he said. "But I must say that the imagination and suspicion of countries in the Middle East regarding what is there are beneficial to Israeli deterrence, and Israel was wise enough throughout the years to keep the ambiguity policy."

Israel has two nuclear reactors, one at Dimona, in the Negev desert, and the other at its nuclear research facility at Nahal Sorek, west of Jerusalem.

The Jewish state is widely believed to have around 200 nuclear warheads, but has a policy of neither confirming nor denying that, a stance which it calls "nuclear ambiguity."

Nahal Sorek is open to international inspection but Dimona is not.

Referring to Iran's alleged nuclear arms ambitions, Peres said Israel has "answers" to any threat to Iran but it does not need to take it upon itself to deal with the issue.

"Israel has the answers to the Iranian problem but it is the responsibility of the whole world to solve it," he said. "This can not be transformed into an Israeli monopoly."

A November report by the International Atomic Energy Agency expressed "serious concerns" that Iran "has carried out activities relevant to the development of a nuclear explosive device".

Iran says its nuclear programme is peaceful and rejected the report as "baseless."