A period of high-level diplomacy on the Middle East opens in New York on Monday, promising further insights into an emerging strategy from Barack Obama’s administration that is already raising concerns among Israel’s supporters.

On Monday, King Abdullah of Jordan said the US was promoting a “57-state solution” in which the entire Muslim world would recognise Israel. But he also warned that the new US administration had little time, before fresh violence erupted, to promote a two-state solution to the conflict between Israel and the Palestinians.

A US official last week broke a long-standing taboo by referring to Israel’s nuclear weapons in a speech at the United Nations, and Joe Biden, vice-president, delivered a message to the biggest US pro-Israel lobby group that he warned they were “not going to like”.

The Russians and the US have been working together on a Security Council statement that is almost certain to reaffirm support for a two-state solution to the conflict, something Benjamin Netanyahu, the new Israeli prime minister, has been reluctant to endorse.

”If there is procrastination by Israel on the two-state solution or there is no clear American vision for how this is going to play out in 2009, then all the tremendous credibility that Obama has worldwide and in this region will evaporate overnight if nothing comes out in May,” King Abdullah said in an interview with The Times of London. ”If we delay our peace negotiations, then there is going to be another conflict between Arabs or Muslims and Israel in the next 12-18 months.”

The New York diplomatic round opens with a ministerial-level meeting of the United Nations Security Council, hosted by Sergei Lavrov, Russian foreign minister. David Miliband and Bernard Kouchner, his British and French counterparts, are among other ministers of the 15-state body expected to attend.

Hillary Clinton, US secretary of state, will not be there but the US will be represented at ministerial level by Susan Rice, the US permanent representative at the UN, who is a member of the president’s cabinet.

After a meeting Mr Lavrov on Thursday, Mr Obama said an opportunity existed to reset the relationship between the US and Russia on a range of issues, including nuclear proliferation, Iran and the Middle East.

Mr Netanyahu is due in Washington on May 18 for talks with Mr Obama, who is also due to meet the Egyptian and Palestinian leaders.

A clearer picture of administration policy will not emerge until after that round of meetings. However, Mr Biden set the tone last week when he told the American Israel Public Affairs Committee (Aipac) Israel had to work towards a two-state solution.

He told the lobby group’s annual conference: “You’re not going to like my saying this, but [Israel should] not build more settlements, dismantle existing outposts, and allow the Palestinians freedom of movement ... ”

On the same day, Rose Gottemoeller, US assistant secretary of state, told a non-proliferation meeting at the UN: “Universal adherence to the NPT [nuclear non-proliferation treaty] – including by India, Israel, Pakistan and North Korea – remains a fundamental objective of the United States.”

Urging the four non-signatory nuclear weapon states to join the worldwide treaty did not represent a radical change in policy from previous administrations, but one expert said naming Israel marked a “major shift”. Since the US discovered Israel’s nuclear weapons ­programme in the 1960s, Israel has consistently refused publicly to confirm or deny that it has a nuclear arsenal.

“This is a very big issue to take on,” Stephen P.?Cohen, a former Middle East adviser to the US National Intelligence Council told the Financial Times. He linked the naming of Israel to Mr Obama’s policy of opening dialogue with Iran, which Israel, western and Arab states fear is poised to join the nuclear weapons club.

He said encouraging Israel at least to acknowledge the existence of its nuclear weapons might be part of a strategy to persuade Iran to be more forthcoming and even to claim some credit if it led to reducing nuclear tension in the Middle East.

Tehran has been relatively cool towards Mr Obama’s overtures for a dialogue, while Israel is unhappy at the idea of a US-Iranian rapprochement. “Iran is a threat not just to Israel, but to the whole world,” Shimon Peres, Israeli president, told Aipac last week.

However, Mohammad Ali Hosseini, Iranian deputy foreign minister, cautiously welcomed a shift in US ­policy when he told the non-proliferation meeting in New York: “US officials have recently pledged to change their approach towards nuclear weapons and have expressed their intention to move towards nuclear ­disarmament.”