NEW YORK — The leaders of France, Germany and the United Kingdom on Monday blamed Iran for an attack on oil facilities in Saudi Arabia earlier this month.

"We condemn in the strongest terms the attacks on oil facilities on Saudi territory on September 14th, 2019 in Abqaiq and Khurais, and we reaffirm in this context our full solidarity with the Kingdom of Saudi Arabia and its population," French President Emmanuel Macron, German Chancellor Angela Merkel and U.K. Prime Minister Boris Johnson said in a joint statement after meeting on the sidelines of the United Nations General Assembly.

“It is clear to us that Iran bears responsibility for this attack," the leaders said. "There is no other plausible explanation. We support ongoing investigations to establish further details.”

It was a particularly a sharp rebuke of Tehran by three European powers that have been struggling to preserve the Iran nuclear deal (known as the Joint Comprehensive Plan of Action, or JCPOA) against enormous pressure from Washington.

The public calling out of Iran's culpability will also likely further complicate a recent effort by Macron to defuse tensions over the nuclear deal, and even broker a meeting this week between U.S. President Donald Trump and Iranian President Hassan Rouhani.

Macron, speaking briefly to reporters after his discussion with Merkel and Johnson, said he remains hopeful, and plans to meet separately with Rouhani on Monday evening and Trump on Tuesday.

He called the joint statement "a step that shows that there is clarity," and added: "We are committed, we took our responsibilities by starting in the JCPOA, including when others were leaving it, so we expect that everyone be clear and preserve security in the region.”

Trump has similarly pointed a finger at Iran in the September 14 attack, which caused severe damage at two of Saudi Arabia's most important oil processing facilities and sent world petroleum prices soaring.

In response to the attack, Trump pronounced his country "locked and loaded." In the end, though, he announced a series of stepped-up sanctions intended to punish Tehran for the attack and further toughen U.S. policy toward Iran, which he had already branded "maximum pressure."

The Europeans warned sternly that the bombing of the oil facilities had raised the risk of a dangerous new conflict in the Middle East.

"These attacks may have been against Saudi Arabia but they concern all countries and increase the risk of a major conflict," they said. "We are committed to continuing our diplomatic efforts to create conditions and facilitate dialogue with all relevant partners interested in de-escalation of tensions in the Middle East, in the interest of preserving international peace and security, building upon our joint declaration on July 14, 2019 and G7 conclusions adopted in Biarritz."

They concluded their statement with an appeal to Tehran: “We urge Iran to engage in such a dialogue and refrain from further provocation and escalation."

Iranian officials have repeatedly denied involvement in the drone strike, and warned the West against any reprisal. Rouhani has said the attack was a warning to Saudi Arabia from Yemen over the Saudi kingdom's role in Yemen's civil war.

The joint statement by the Europeans came just hours after the U.K. issued its own assessment of Iran's role.

Earlier on Monday, British Prime Minister Johnson said: "I can tell you that the U.K. is attributing responsibility with a very high degree of probability to Iran for the Aramco attacks." Downing Street said the strikes were conducted using drones and cruise missiles.

Even on his way to New York, Macron had expressed hope that he might still be able to leverage the current situation into an opportunity for renewed diplomacy, and possibly to engage Iran in a conversation not just about returning to compliance with the JCPOA, but also about curbing its role in regional military conflicts and limiting its conventional ballistic missile program.

But ahead of the summit, Johnson called for a new “Trump deal” on Iran.

In an interview with NBC, he said the existing nuclear agreement was a “bad deal” with “many defects” and argued the U.S. president was the “one guy” who could renegotiate it.

“I think there’s an opportunity now, if everyone can de-escalate for us all — that’s to say the Europeans, the U.K., plus the United States and others — to look at a successor to that deal. If it was a bad deal — and I’m willing to accept that, it had many, many defects — then let’s do a better deal.”

Johnson continued: “And I think there’s one guy who can do a better deal and one guy who understands how to get a difficult partner like Iran over the line and that is the president of the United States.

“So I hope that there will be a Trump deal, to be totally honest with you.”

A U.K. government official said: “The Iranians aren't currently in compliance and we need to bring them back into compliance. If there's a way to do that we're open to discussing possible solutions.”

The appeal to Trump could be a gambit to get the president, who is known for responding to flattery around the negotiating table — a possibility that might help explain Johnson’s seemingly contradictory joint statement with Macron and Merkel, in which he expressed commitment to the JCPOA.

Indeed, Trump appeared intrigued by the prospect of a new deal in a White House pool clip, saying he was “not at all surprised that [Johnson] was the first one to come out and say that.”

“That's why he's a winner,” the president told a White House pool reporter. “That's why he's a man who’s going to be successful in the U.K.”

Trump added that the existing Iran deal was set to too short a time frame, and that it lacked sufficient inspection rights of Iranian development sites.

Iran has pulled back from its commitments under the nuclear deal in response to Trump's unilateral withdrawal from the JCPOA and the inability of the European guarantors to maintain the economic benefits that Iran had been promised in exchange for tight controls and monitoring of its nuclear program.

Emilio Casalicchio contributed reporting.