Former US President Jimmy Carter defended his harsh criticism of Israeli policy in his latest book, saying he hopes to erode the "impenetrable wall" that blocks the American public from seeing the plight of Palestinians. The top-selling book, "Palestine: Peace Not Apartheid," has been criticized by pro-Israel groups and led to the resignation, announced this week, of Kenneth Stein, a Carter Center fellow and a longtime Carter adviser. Carter said Friday that he intended the book to provoke debate on Israeli policy that has been stifled by the news media and others, who have been "almost unanimously silent." "It's almost a universal silence concerning anything that might be critical of current policies of the Israeli government," he said. Carter's words have led to an outcry among Jewish groups, who have launched petitions criticizing his use of the word "apartheid" - the system of legal racial separation once used in South Africa - to describe Israel's treatment of Palestinians. Carter, though, said he stands by his use of the word, and cited the sprawling complex of fences, electric sensors and concrete slabs that Israel built along the West Bank as an example of the divide. "I think it's worse, in many ways, than apartheid in South Africa," Carter said. The book follows the Israeli-Palestinian peace process, starting with Carter's 1977-1980 presidency and the Camp David peace accord he negotiated between Israel and Egypt. It blames Israel, the Palestinians, the US and others, but it is most critical of Israeli policy. Stein, an Emory University professor, sent a letter to Carter claiming the book was "one-sided" and "is not based on unvarnished analysis; it is replete with factual errors, copied materials not cited, superficialities, glaring omissions, and simply invented segments." Carter said Friday that Stein had not played a role in the Carter Center in 13 years and that his post as a fellow was an honorary title. "When I decided to write this book, I didn't even think about involving Ken, from ancient times, to come in and help." He also said his book was vetted by Carter Center staff as well as an unnamed "distinguished" reporter. Carter, who won the Nobel Peace Prize in 2002, lamented the lack of debate over Israeli policy in the US. "There's a tremendous intimidation in this country that has silenced our people. And it's not just individuals, it's not just folks who are running for office. It's the news media as well," he said. Carter, who has led efforts to monitor several elections in the Palestinian Authority since leaving office, said bringing peace to the Middle East is the most important commitment in his public life. He also said his book was vetted by Carter Center staff as well as an unnamed "distinguished" reporter.