WARSAW (Reuters) - U.S. Vice President Mike Pence accused European powers on Thursday of undermining Washington’s crack down on Iran by trying to break U.S. sanctions against Tehran, in remarks that were likely to further strain transatlantic relations.

Pence spoke at a Middle East peace conference in Warsaw attended by 60 countries, notably including both Gulf Arab states and Israel, in what Israeli Prime Minister Benjamin Netanyahu called a “historical turning point” for an alliance against Tehran. Iran, Russia and the Palestinians were absent.

European powers, who oppose the Trump administration’s decision to pull out of a nuclear deal with Iran, were openly skeptical of a conference excluding Tehran. France and Germany declined to send their top diplomats, while British Foreign Secretary Jeremy Hunt left before Thursday’s main events.

“Sadly, some of our leading European partners have not been nearly as cooperative,” Pence said. “In fact, they have led the effort to create mechanisms to break up our sanctions.”

Trump pulled the United States last year out of the 2015 Iran deal, under which Tehran agreed to curbs on its nuclear program in return for the lifting of sanctions.

European countries say they share Washington’s concerns about Iran’s regional behavior but believe withdrawing from the nuclear deal was a mistake, and have promised to try to salvage the deal as long as Iran continues to abide by it. In practice, European companies have accepted new U.S. sanctions on Iran and abandoned plans to invest there.

Pence called on the Europeans to follow Washington and exit the agreement: “The time has come for our European partners to withdraw from the Iran nuclear deal and join with us.”

He said a new European scheme to trade with Iran, known as the Special Purpose Vehicle, was “an effort to break American sanctions against Iran’s murderous revolutionary regime”.

“It is an ill-advised step that will only strengthen Iran, weaken the EU and create still more distance between Europe and the United States,” he said.

U.S. Vice President Mike Pence and Israeli Prime Minister Benjamin Netanyahu shake hands as they meet in Warsaw, Poland, February 14, 2019. REUTERS/Kacper Pempel

The mechanism was conceived as a way to help match Iranian oil and gas exports against purchases of EU goods. However, those ambitions have been scaled back, with diplomats saying that, realistically, it will be used only for trade, for example of humanitarian products or food, allowed by Washington.

European diplomats at the conference rejected Pence’s accusations: “We strongly disagree,” a diplomat from a major European power said. “We want to push Iran to good results and don’t want to push Iran outside of its nuclear commitment.”

The summit venue in Poland could itself be seen as a rebuke to Washington’s traditional Western European allies, who are at odds with a nationalist government in Warsaw over moves the EU says curb judicial independence and free speech.

U.S. Secretary of State Mike Pompeo is due to travel to Brussels on Friday for talks with Federica Mogherini, the EU’s foreign policy chief. Pompeo told a news conference there were differences during the summit meeting over how to get Iran to change its ways, but there was unanimity, including from Europeans, that Tehran posed a global threat.

“We make no bones about it, we need more sanctions, more pressure on Iran,” Pompeo said in closing remarks. “There was not a defender of Iran in the room. No country. No country spoke out and denied any of the basic facts that we have all laid out about Iran, the threat it poses, the nature of regime.”

The summit was notable because of the presence of Israel alongside wealthy Arab states Saudi Arabia, Kuwait, Oman, Qatar, United Arab Emirates and Bahrain. Washington aims to narrow differences between its Israeli and Arab allies to isolate Iran.

“DESPERATE CIRCUS”

But just as notable were the absences, not only of Iran itself -- which called the meeting a “desperate circus” -- but of the Palestinians, who refused to attend over what they regard as U.S. bias against them under Trump. They have been boycotting the administration since Trump reversed decades of U.S. policy in 2017 to recognize Jerusalem as the capital of Israel.

Chief Palestinian Negotiator Saeb Erekat took aim at the Arab states for attending, citing an Arab meeting last year that reaffirmed demands that Israel first withdraw from Palestinian land before it can normalize ties with Arab countries.

“Reward the occupation, the decision to abolish the Arab Peace Initiative and the decisions of the Dhahran Summit. For what? Mediation between America and Israel on the one hand and Iran on the other,” Erekat tweeted.

Nabil Abu Rudeineh, spokesman for Palestinian President Mahmoud Abbas, said the only path to peace was by negotiating with the Palestinian leadership represented by Abbas.

Niels Annen, Germany’s minister of state, was skeptical that the conference would deliver results on Iran.

“I am hoping for constructive signals but nobody here has the expectation that this conference will solve problems,” he told reporters on the sidelines of the meeting. “That would be unrealistic because we need a political agreement with all participants at the end of the day.”

Earlier, Pompeo called for an era of cooperation during opening remarks that were broadcast publicly. The rest of the meeting, including a presentation by White House advisor and Trump son-in-law Jared Kushner on plans for Israeli-Palestinian peace, was held behind closed is doors.

Kushner told the audience that the United States would not unveil the plan until after an Israeli election on April 9.

Kushner and Trump’s Middle East envoy Jason Greenblatt are trying to broker a peace plan to cover all core issues of the decades-old conflict between Israel and the Palestinians, U.S. official say. Release of the plan has been delayed by Palestinian anger at Trump’s change of U.S. policy on Jerusalem.