WASHINGTON (Reuters) - Egypt, Jordan and Morocco have informed the Trump administration they will attend a U.S.-led conference in Bahrain this month on proposals for boosting the Palestinian economy as part of a coming U.S. peace plan, U.S. officials said on Tuesday.

FILE PHOTO: A woman holding a Palestinian flag gestures in front of Israeli forces during a protest marking the 71st anniversary of the 'Nakba', or catastrophe, when hundreds of thousands fled or were forced from their homes in the war surrounding Israel's independence in 1948, at the Israel-Gaza border fence, in the southern Gaza Strip May 15, 2019. REUTERS/Ibraheem Abu Mustafa/File Photo

Egypt and Jordan’s participation is considered especially important since historically they have been key players in Israeli-Palestinian peace efforts and are also the only Arab states to have reached peace agreements with Israel.

However, Palestinian leaders’ decision to boycott the June 25-26 conference in Manama has raised doubts about its chances for success. They have shunned a broader diplomatic effort widely referred to as U.S. President Donald Trump’s “deal of the century” but which Palestinians see as likely to be heavily tilted in favor of Israel and denying them a state of their own.

In a letter dated June 10 to foreign diplomats in the Palestinian areas, Saeb Erekat, secretary-general of the Palestine Liberation Organization, said: “Our presence in Manama would only be used as a legitimization of the initiative that aims at depriving us of our rights.”

Despite that, White House senior adviser Jared Kushner, Trump’s son-in-law and a chief architect of the long-delayed peace plan, is pressing ahead with arrangements for the Bahrain meeting, where the economic components are expected to be unveiled as the first step in the plan’s rollout.

Acceptance of the invitation to the conference by Jordan and Egypt will bring to the table two countries that border both Israel and Palestinian areas.

Saudi Arabia, Qatar and the United Arab Emirates have previously confirmed their attendance, a White House official said.

The official declined to say what level of representation the countries would send. U.S. officials have said they were inviting economic and finance ministers, as well as business leaders from the region and around the world, to discuss investment in the troubled Palestinian economy in the Gaza Strip and West Bank.

Global financial bodies including the International Monetary Fund and World Bank also plan to be present.

U.S. officials have been vague about the timing for the second phase of their initiative, which would be the release of proposals for resolving thorny political issues at the core of the Israeli-Palestinian conflict.

With Israel heading for new elections in September after Prime Minister Benjamin Netanyahu failed to meet a deadline to form a government, uncertainty is expected to further delay the full release of the plan.

Most experts are skeptical the Trump administration can succeed where decades of U.S.-backed efforts have failed.

The Palestinian leadership has rejected diplomatic contacts with the Trump administration since it recognized Jerusalem as Israel’s capital in late 2017 and then moved the U.S. embassy there from Tel Aviv. Palestinians want the eastern part of the city, captured by Israel in the 1967 war and annexed in a move not recognized internationally, as their future capital.