Israel accused Iran Thursday of being the biggest nuclear threat to the Middle East as it sought to deflect pressure over its own, undeclared possession of atomic arms.

Iran shot back by claiming Israel’s undeclared atomic arsenal was the most serious threat.

The two nations argued at a 155-nation meeting of the International Atomic Energy Agency (IAEA). The sharply worded debate reflects tensions between Israel and Iran that could spiral into armed conflict.

The US and its allies accuse Tehran of trying to develop the capacity to make nuclear weapons and say that is the greatest menace to the region.

Israeli delegate Ehud Azoulay said Iran “represents the greatest threat to peace and security in the Middle East and beyond.”

But Iran’s envoy to the IAEA, Ali Asghar Soltanieh, said Israel’s refusal to join the Nuclear Non-Proliferation Treaty posed a threat to the Middle East.

“At present the Israeli regime is the only non-party to the NPT in this area, despite repeated calls by the international community,” he said, according to AFP. “The irresponsible behavior of this (Israeli) regime… has put the establishment of a [nuclear-free] zone in the region for the near future in serious doubt.”

Israel, which maintains an official policy of ambiguity over its nuclear capabilities, reportedly rebuffed calls this week to attend a summit sponsored by Finland on making the Middle East a nuclear weapon-free zone, despite international pressure to attend.

Earlier, Israel’s atomic energy chief used the podium at the Vienna confab to call on Iran to stop issuing threats, saying the Jewish state was well equipped to fight back. “Israel is competent to deter its enemies and to defend itself,” Shaul Horev said.

Iran and the IAEA are currently engaged in talks over access to the Parchin nuclear site, which is suspected to be a military site used for testing nuclear weapons. Earlier in the week, Iran attempted to divert pressure over the issue by accusing the IAEA of harboring terrorists who attempted to sabotage its Fordo complex, also thought to be a key part of its nuclear-weapon program.

Iran also came under pressure from the Security Council Thursday, where the US, Britain and France warned the Islamic Republic that time was running out to find a diplomatic solution for Iran’s enrichment activities.