US Vice President Mike Pence has accused leading European countries of trying to break US sanctions against Tehran in remarks at a Middle East peace summit that are likely to further strain transatlantic relations.
Pence spoke at the conference in Warsaw attended by 60 countries, including Israel and six Gulf Arab states, but not the Palestinians or Iran.
European powers, who oppose the Trump administration's decision to pull out of a nuclear deal with Iran, were openly sceptical 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 co-operative," Pence said on Thursday.
"In fact, they have led the effort to create mechanisms to break up our sanctions."
Trump last year pulled the US 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 the move 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 US sanctions on Iran and abandoned plans to invest there.
Pence said a 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.
The summit was notable because of the presence of Israel alongside wealthy Arab states. Washington aims to narrow differences between its Israeli and Arab allies to isolate Iran.
Israeli Prime Minister Benjamin Netanyahu called the conference a "historical turning point" in combating the threat from Iran.
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 US bias against them under Trump.
They have been boycotting the administration since Trump reversed decades of US policy in 2017 to recognise 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 normalise ties with Arab countries.
US Secretary of State Mike Pompeo called for an era of cooperation at opening remarks that were broadcast publicly. The rest of the meeting, including a presentation by White House adviser and Trump son-in-law Jared Kushner on plans for Israeli-Palestinian peace, was held behind closed is doors.
Australian Associated Press