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JERUSALEM — Mitt Romney found himself on the defensive yet again on his overseas trip, this time after offending Palestinian leaders with comments he made at a breakfast fund-raiser here on Monday.

Speaking to roughly four dozen donors at the King David Hotel in Jerusalem, Mr. Romney suggested that cultural differences between the Israelis and the Palestinians were the reason the Israelis were so much more economically successful than the Palestinians, without mentioning the impact that deep trade restrictions imposed by the Israeli government have had on the Palestinian economy. He also vastly understated the income disparities between the two groups.

In his speech, Mr. Romney mentioned two books that had influenced his thinking about nations — “Guns, Germs and Steel,” by Jared Diamond, and “The Wealth and Poverty of Nations,” by David S. Landes. Mr. Diamond’s book, Mr. Romney said, argues that the physical characteristics of the land account for the success of the people living there, while Mr. Landes’s book, he continued, argues that culture is the defining factor.

“Culture makes all the difference,” Mr. Romney said. “And as I come here and I look out over this city and consider the accomplishments of the people of this nation, I recognize the power of at least culture and a few other things.”

“As you come here and you see the G.D.P. per capita, for instance, in Israel which is about $21,000, and compare that with the G.D.P. per capita just across the areas managed by the Palestinian Authority, which is more like $10,000 per capita, you notice such a dramatically stark difference in economic vitality,” he said.

In an interview with The Associated Press, Saeb Erekat, a senior aide to President Mahmoud Abbas of the Palestinian Authority, called Mr. Romney’s remarks “racist.”

“It is a racist statement and this man doesn’t realize that the Palestinian economy cannot reach its potential because there is an Israeli occupation,” Mr. Erekat said. “It seems to me this man lacks information, knowledge, vision and understanding of this region and its people.”

The Palestinians live under deep trade restrictions put in place by the Israeli government: After the militant group Hamas in 2007 took control of Gaza – home to about 1.7 million Palestinians – the Israelis imposed a near-total blockade on people and goods in Gaza. The blockade has been eased, and now many consumer goods are allowed in. But aid organizations say the restrictions still cripple Gaza’s economy. The West Bank, where 2.5 million Palestinians reside, is also subject to trade restrictions imposed by the Israelis.

In Gaza, according to the C.I.A., “Israeli-imposed border closures, which became more restrictive after Hamas seized control of the territory in June 2007, have resulted in high unemployment, elevated poverty rates, and the near collapse of the private sector that had relied on export markets.” The agency added that “changes to Israeli restrictions on imports in 2010 resulted in a rebound in some economic activity, but regular exports from Gaza still are not permitted.” And in the West Bank, “Israeli closure policies continue to disrupt labor and trade flows, industrial capacity, and basic commerce, eroding the productive capacity” of the economy.

On Monday afternoon, Romney campaign officials did not respond to a query about whether Mr. Romney believes that the blockade of Gaza or trade restrictions in the West Bank have had any dampening effect on economic activity in those areas.

Mr. Romney also understated the difference between per capita G.D.P. by a wide margin, suggesting that Israelis produce about twice what Palestinians do.

In fact, according to an estimate by the Central Intelligence Agency, in 2009 Israel had a per capita G.D.P. of roughly $29,800, while in 2008 — the last year the C.I.A. has numbers on their Web site for the Palestinians — the per capita G.D.P. of the West Bank and Gaza was $2,900.

Though Mr. Romney came to Israel to offer his support for the country, delivering a speech Sunday night in Jerusalem in which he offered a strong defense of Israel’s right to protect itself against the threat of a nuclear Iran, Mr. Romney also met Sunday with the Palestinian Authority’s prime minister, Salam Fayyad. In public, the two men made small talk about the London Olympics.

After Mr. Romney’s remarks drew criticism, his campaign said that The Associated Press had “grossly mischaracterized” the remarks by not providing the full context. For instance, the campaign said, after mentioning the per capita G.D.P. of Israel and Palestine, Mr. Romney also said: “And that is also between other countries that are near or next to each other. Chile and Ecuador, Mexico and the United States.”

The comments Monday are the second time that Mr. Romney has unwittingly offended a group of people in a part of the world he was visiting. When he arrived in London on the first stop of his trip, Mr. Romney set off a media firestorm when he seemed to cast question on the city’s preparedness for the Olympic Games.

Obama campaign officials criticized Mr. Romney’s latest remarks, describing them as the sort of thing that could make it more difficult for Mr. Romney to ever play a credible role in the Middle East peace process, which depends on having buy-in not from just Israelis but from Palestinian officials as well.

American credibility and influence in that arena depend on “us being seen as an honest broker,” said Colin Kahl, an Obama campaign foreign policy adviser who served as the top Middle East policy official in the Pentagon from 2009 to 2011. “But in this case, Romney fell off the tightrope pretty dramatically.”

“It was a really strange comment,” Mr. Kahl added, noting that the Israeli-Palestinian conflict encompasses “extraordinarily complicated and delicate issues and is not something you can just wing it on and expect not to make some mistakes, and Governor Romney made a big one.”