Do Palestinian school textbooks "teach terrorism," as Newt Gingrich claimed in a recent debate among U.S. Republican presidential hopefuls?

His example - that Palestinians "have text books that say, `If there are 13 Jews and nine Jews are killed, how many Jews are left?'" - is not in any of the texts, researchers say.

As for Gingrich's broader claim, the textbooks don't directly encourage anti-Israeli violence, but they also don't really teach peace, studies say.

A review of some texts by The AP, as well as several studies by Israeli, Palestinian and international researchers, found no direct calls for violence against Israel. However, the books lack material about the historic Jewish presence in the region and scarcely mention Israel and then mostly in a negative way. Peace with Israel rarely comes up. Texts for religious schools are harder-core, openly glorifying martyrdom.

Researchers disagree sharply in their interpretation of the material.

Two NGOs, one Israeli and one international, support the view of Israeli officials that the texts promote hatred of Israel. For example, Israel is not included in a list of the countries of the Levant, and Hebrew writing was removed in a depiction of a stamp from British Mandate rule of the Holy Land.

A joint Israeli-Palestinian study takes a softer view, saying that there is no direct attempt to delegitimize Israel, but that "the way and contexts in which Israel is presented may give rise to the impression of an implicit denial of its legitimacy."

The books must be seen in the context of ongoing conflict, said Nathan Brown, a George Washington University political scientist who has written about the issue. While highly nationalistic, government texts don't glorify violence, explicitly deny Israel's right to exist or portray Jews as villains, he said.

"I think the textbook critics have cause and effect mixed up - when there is a viable political process it may be possible to introduce a process to revise the books in a reciprocal way," Brown said.

The argument looms large in a debate driven by the Israeli government, which frequently accuses the Palestinians of incitement in their schools.

"How can you take someone seriously as a partner in peace, if instead of teaching their children reconciliation they teach hate," said Israeli government spokesman Mark Regev. "It's the heart of the matter."

The Palestinians say their books legitimately focus on their national narrative, including hardships of life under occupation. "We might have a problem with Zionism, but this is not incitement, this is a difference in views," said Ghassan Khatib, spokesman of the Palestinian Authority, which controls part of the West Bank.

Palestinian officials say Israel has created an artificial issue in hopes of diverting attention from its failure to meet key peace obligations, such as halting its settlement of occupied lands.

The question has suddenly become an issue in the U.S. presidential campaign. Three researchers - Brown, Itamar Marcus from Palestinian Media Watch and Eldad Pardo from IMPACT-SE - said the example Gingrich cited in the Dec. 10 Republican debate does not exist in the texts. Gingrich's office did not respond to two emailed requests for further comment.

Greater clarity could arise from a State Department-funded review of both Israeli and Palestinian textbooks to be released in the spring. Since 2009, Israeli and Palestinian researchers, fluent in Hebrew and Arabic, have been examining 370 Israeli and 102 Palestinian books from grades 1-12. Some of the Palestinians review Israeli books, and some of the Israelis review Palestinian books.

Conclusions are left to the study's sponsor, the Council of Religious Institutions in the Holy Land, made up of clerics representing Judaism, Islam and Christianity, said Yale professor Bruce Wexler, overseeing the research.

Some argue that Israeli textbooks also promote a national narrative, noting that the so-called Green Line, the pre-1967 war frontier between Israeli and the West Bank, has been erased from the Israeli school atlas. The Green Line is also absent from most Palestinian textbooks, but was restored in a Palestinian atlas published several years ago, said geography professor Izhak Schnell of Tel Aviv University.

Texts taught in secular Israeli schools continue to promote the Jews' right of return, but more space than in the past is now allocated to the Palestinians and their pain, said Ruth Firer, of Hebrew University.

Since it took control of parts of the West Bank and Gaza Strip in 1994, the Palestinian Authority has been working to replace the Egyptian and Jordanian books used in its schools for decades previous. Under intensive scrutiny from Israel and the international community, the Palestinians developed their own curriculum and purged their new textbooks of some controversial references, but kept the focus on the Palestinian narrative.

Palestinian Media Watch and IMPACT-SE harshly criticized the Palestinian textbooks.

"There is a lot of jihad, martyrdom, a complete ignoring of anything Israeli," said Pardo, a Hebrew University of Jerusalem professor and member of IMPACT-SE. "There is no education for peace, there is education for conflict."

Many of the most problematic passages IMPACT-SE cited came from the texts for Islamic religious schools. Only about 750 of the 1.16 million students enrolled in Palestinian schools in the West Bank, Gaza and east Jerusalem attend such schools.

Shelley Elkayam of IMPACT-SE said the religious school students are influential since they go on to be religious teachers and preachers.

The textbooks include statements glorifying martyrdom. One 8th-grade text says Muslim fighters must "get rid of the usurping Jews from the usurped lands in Palestine and in the Levant."

The Palestinian Education Ministry only began supervising the Islamic schools a year ago and is gradually replacing the old texts with new ones "based on moderation," said Mohammed Jihad, head of the religious school system.

A new 12th grade book, for example, provides a nonviolent definition of jihad - a way of spreading justice.

In government schools - attended by 768,000 students - a number of passages glorifying jihad were removed, IMPACT-SE acknowledged. Still, it said, the books are problematic. For example, a 12th grade Islam studies book discusses the concept of "ribat," or steadfastness against attackers, saying Palestinians "are in steadfastness until the day of resurrection." Elkayam said this suggests the struggle over Palestine is eternal.

"Although there is no direct instruction for immediate violence against Israelis ... hate, rejection and a vision of one Greater Islamic-Arab Palestine are fostered," said the study, which was released in May and reviewed 70 government textbooks and 25 religious school texts. "An imaginary geography in which Israel does not exist is being taught."

The joint Israeli-Palestinian study of 2006, commissioned by IPCRI, a dovish nonprofit group, highlighted some positive elements of the new textbooks, saying they do not "incite hatred toward Jews or Judaism" and that only two cases of anti-Jewish stereotypes were found.

But no objective information is found about Israel's society and people, it said.

Khatib, the Palestinian Authority spokesman, defended the omission of Israel from Palestinian textbooks. "When Israel is going to include us in their textbooks, we will include them in our textbooks," he said. "It is supposed to be a mutual thing."