Iranian demonstrators react after the IRGC attack on Israel, during an anti-Israeli gathering in front of the British Embassy in Tehran, Iran, Sunday. (West Asia News Agency-Reuters)

Countries around the world condemned Iran's strikes on Israel late Saturday, warning the attack threatened to further destabilise the Middle East.

Here are some of the main reactions so far:

US - US President Joe Biden promised "ironclad" support for Israel after holding an urgent meeting with top security officials.

"I just met with my national security team for an update on Iran's attacks against Israel. Our commitment to Israel's security against threats from Iran and its proxies is ironclad," Biden said on X, posting a picture of the meeting in the White House Situation Room.

Britain - UK Prime Minister Rishi Sunak condemned the "reckless" strikes, which he said "risk inflaming tensions and destabilising the region. Iran has once again demonstrated that it is intent on sowing chaos in its own backyard."

European Union - The European Union's foreign affairs chief Josep Borrell said the strikes were "an unprecedented escalation and a grave threat to regional security" in a message on X.

United Nations - UN Secretary-General Antonio Guterres condemned "the serious escalation represented by the large-scale attack launched on Israel by the Islamic Republic of Iran."

"I am deeply alarmed about the very real danger of a devastating region-wide escalation," he added, calling on parties to "avoid any action that could lead to major military confrontations on multiple fronts in the Middle East."

Egypt - Cairo's foreign ministry expressed its "deep concern" at the escalation of hostilities and called for "maximum restraint."

The ministry's statement also warned of the "risk of the regional expansion of the conflict," and added that Egypt would be "in direct contact with all parties to the conflict to try and contain the situation."

Saudi Arabia - The Saudi foreign ministry issued a statement voicing its concern at the "military escalation" and calling on "all parties to exercise utmost restraint and spare the region and its peoples from the dangers of war."

It went on to urge the UN Security Council "to assume its responsibility towards maintaining international peace and security."

China - China's foreign ministry also urged restraint, characterising the attack as "the latest spillover of the Gaza conflict" and calling for the implementation of a recent UN Security Council resolution demanding a ceasefire there, saying the "conflict must end now." "China calls on the international community, especially countries with influence, to play a constructive role for the peace and stability of the region," it added.

France - France's Foreign Minister Stephane Sejourne on X said that "in deciding to take this unprecedented action, Iran has reached a new level in its acts of destabilisation and is risking a military escalation."

Germany - Berlin's top diplomat also warned the attack would have a destabilising effect, and urged Tehran to halt the strikes. "We condemn the ongoing attack -- which could plunge an entire region into chaos -- in the strongest possible terms," Foreign Minister Annalena Baerbock said on X. "Iran and its proxies must stop this immediately," she continued, adding that Berlin stands "firmly by Israel."

Canada - Canadian Prime Minister Justin Trudeau told reporters in Ottawa that his country "unequivocally condemns Iran's airborne attacks," adding: "We stand with Israel."

"After supporting Hamas' brutal October 7 attack, the Iranian regime's latest actions will further destabilise the region and make lasting peace more difficult," he added.

Spain - Spanish Prime Minister Pedro Sanchez called for restraint, saying on X: "We are following with the greatest concern the evolution of the situation in the Middle East. One must at all cost avoid a regional escalation."

Argentina - The office of Argentine President Javier Milei expressed its "solidarity and unwavering commitment" to Israel in the face of the attacks.

It added that Argentina "emphatically supports the State of Israel in the defence of its sovereignty, especially against regimes that promote terror," noting an Argentine court recently held Iran responsible for bomb attacks on the Israeli embassy and a Jewish community centre in Buenos Aires in the 1990s.

Ukraine - Ukraine's foreign ministry said Kyiv "strongly condemns Iran's massive air attack" saying it could lead to "further grave acceleration in the Middle East." "The attack also demonstrates why it is critical that all of the free world's forces are consolidated to defend the global borders of democracy."