UNITED NATIONS — Britain, France and Germany joined the United States on Monday in blaming Iran for attacks on key oil facilities in Saudi Arabia, but the Iranian foreign minister pointed to claims of responsibility by Yemeni rebels and said: “If Iran were behind this attack, nothing would have been left of this refinery.”

Fallout from the Sept. 14 attacks is still reverberating as world leaders gather for their annual meeting at the U.N. General Assembly and international experts continue, at Saudi Arabia’s request, to investigate what happened and who was responsible.

The leaders of the U.K., France and Germany — who remain parties to the 2015 Iran nuclear deal — said in a statement that “there is no other plausible explanation” than that “Iran bears responsibility for this attack.”

British Prime Minister Boris Johnson said late Sunday while flying to New York that the U.K. is now “attributing responsibility with a very high degree of probability to Iran” for the attacks by drones and cruise missiles on the world’s largest oil processor and an oil field. He said the U.K. would consider taking part in a U.S.-led military effort to bolster Saudi Arabia’s defenses.

Iran’s foreign minister, Mohammad Javad Zarif, denied any part in the attacks. He said Yemen’s Houthi rebels, who claimed responsibility, “have every reason to retaliate” for the Saudi-led coalition’s aerial attacks on their country.

He also stressed that on the eve of President Hassan Rouhani’s visit to the United Nations — which sits in the middle of New York City — “it would be stupid for Iran to engage in such activity.”

France has been trying to find a diplomatic solution to U.S.-Iranian tensions, which soared after the Saudi attacks.

French President Emmanuel Macron said at a news conference at the U.N. that he planned to meet separately with both Trump and Rouhani over the next day and would work to foster “the conditions for discussion” and not escalation.

Macron called the Sept. 14 strikes “a game-changer, clearly” but reiterated France’s willingness to mediate.