The attacks followed weeks of sabre-rattling and a major US military build-up in the Middle East, and saw Tehran retaliate with a barrages of missiles at Gulf states and Israel.

"These attacks are totally irresponsible and risk provoking further escalation as well as increasing the danger of nuclear proliferation and the use of nuclear weapons," ICAN's executive director Melissa Parke said in a statement.

"Military action is not a viable or long-term solution to prevent nuclear proliferation. All military action must stop immediately."

Geneva-based ICAN won the 2017 Nobel Peace Prize for its key role in drafting the Treaty on the Prohibition of Nuclear Weapons, which took effect in 2021.

The group said the strikes -- two days after the United States and Iran held indirect talks in Geneva on Tehran's nuclear programme -- could snowball into a broader regional war.

The attacks on Saturday came after US President Donald Trump expressed frustration at Iran's stance in the negotiations.

"The solution to ending both the risk of nuclear proliferation and the use of nuclear weapons is for all countries, including the nuclear-armed states, such as the United States and Israel, to join the Treaty on the Prohibition of Nuclear Weapons," said Parke.

ICAN said international treaties such as the TPNW and the Nuclear Non-Proliferation Treaty had provisions for verifiable nuclear disarmament and non-diversion of nuclear material for weapons.

"The TPNW is the best way to ensure nuclear weapons are never used and to remove any incentive for more countries to develop them," said Parke.