PARIS — Forty-three nations, including Israel and Arab states, pledged Sunday to work for a Middle East free of weapons of mass destruction at the close of a summit to launch an unprecedented Union for the Mediterranean aimed at securing peace across the restive region.

In a final declaration, Israel, Syria, the Palestinians along with countries across Europe, the Middle East and North Africa agreed to "pursue a mutually and effectively verifiable Middle East Zone free of weapons of mass destruction."

The countries committed to "consider practical steps to prevent the proliferation" of nuclear, chemical and biological weapons and their delivery systems. It was unclear, however, how the signatories — who included Israeli Prime Minister Ehud Olmert and Syrian President Bashar Assad — would enforce the pledge.

Israel is widely believed to have a stockpile of nuclear weapons but neither confirms nor denies it has them — an ambiguity meant to scare potential enemies from considering an annihilating attack while denying them the rationale for developing their own nuclear deterrent.

Recently, tensions between Israel and archenemy Iran have risen over Tehran's nuclear program. Iranian President Mahmoud Ahmadinejad has often spoken of wiping Israel off the map. And Israel and ally the United States believe Tehran's nuclear program is aimed at producing nuclear weapons, despite Iran's insistence it is for producing nuclear energy.

Syria, another Israeli foe, may also have nuclear ambitions. Last year, Israeli jets destroyed what U.S. intelligence officials said was believed to be a partially built nuclear reactor in Syria, though Syrian officials said it was part of a non-nuclear military program.

While trying to unify the region, the summit laid bare the deep divisions that still slice through it and highlighted how hard it will be to parlay the meeting's goodwill and words into real progress. Syria's president refused to shake the Israeli prime minister's hand, and Morocco's king snubbed the meeting attended by the president of rival Algeria.

Still, summit host Nicolas Sarkozy, France's president, reveled at having brought so many leaders to the same table for the first time.

"We dreamed about a Union for the Mediterranean, and now it is a reality," Sarkozy said in closing the summit in a palace abutting the River Seine. He called it an "extremely moving, very important moment."

The summit declaration also condemned "terrorism in all its forms" and announced six major projects, from a common university and easier travel visas for students to depolluting the Mediterranean sea and promoting solar power.

It also spoke of democratic principles, human rights and fundamental freedoms — values Western critics have accused such union members as Syria of violating.

Sarkozy went to special efforts to bring Syria into the international fold for the summit: Assad met Lebanese President Michel Suleiman and German Chancellor Angela Merkel, separately, both for the first time. And he met Sarkozy after years of chill between their countries.

Egypt's President Hosni Mubarak, co-presiding at the summit with Sarkozy, called on the new union to tackle reducing the wealth "gap" between north and south, and cited other southern Mediterranean "challenges" as education, food safety, health and social welfare.

He said the union has better chances of success than a previous cooperation process launched in Barcelona in 1995 because the new body focuses on practical projects parallel to efforts toward Mideast peace.

The Union for the Mediterranean is Sarkozy's brainchild and was timed to coincide with the French presidency of the European Union. Paris holds the rotating post until the end of this year.

But Sarkozy's ambitious plan overlapped with EU projects already in progress, and it was melded into EU efforts and expanded to include 27 members of the EU, not just those on the Mediterranean coast.

The new union is to include at least 43 nations, nearly all of which sent a president or prime minister to the summit. Libyan leader Moammar Gadhafi objected to the whole idea and refused to come.