Hundreds of American rabbis have put weight behind the historic nuclear agreement reached between Iran and the six world powers in July.

In a letter to US lawmakers on Monday, 340 rabbis called on Congress to approve the July 14 accord.

"We encourage the members of the Senate and the House of Representatives to endorse this agreement," they said in the letter distributed by Ameinu, a progressive charitable Jewish organization.

"We are deeply concerned with the impression that the leadership of the American Jewish community is united in opposition to the agreement," they added. "We, along with many other Jewish leaders, fully support this historic nuclear accord."

Congress is scheduled to vote on the agreement in September.

Republican lawmakers have expressed their opposition to the deal, but President Barack Obama is hopeful that his fellow Democratic allies in both chambers support him.

Forty-nine rabbis who signed the letter are from New York, where Democratic Senator Chuck Schumer said he would vote against the agreement.

Israel has publicly opposed the nuclear agreement reached between Iran and the P5+1 group -- the United States, Britain, France, China, Russia and Germany – in Vienna last month.

Earlier this month, Israeli Prime Minister Benjamin Netanyahu urged Jewish leaders to condemn the conclusion of the nuclear negotiations.

Obama has repeatedly criticized Netanyahu for his opposition to the accord and his efforts to block it in Congress.

American lawmakers are widely expected to reject the agreement, but it would take a two-thirds vote in both the House and Senate to override a presidential veto.