In the wake of a purported al-Qaida letter threatening to "clash with Israel," the Foreign Ministry has expressed increased concerns of al-Qaida crossing Israel's border, while a leading expert on global jihad has cast doubt on the letter's authenticity. "What we have seen in the recent past are the efforts by al-Qaida to build a presence in Israel and on Israel's borders in order to act upon their extremist ideology," Foreign Ministry spokesman Mark Regev told The Jerusalem Post in response to a query. "Obviously we are increasingly concerned about Al-Qaida activities in the region and we follow them closely," he said. The 6,300-word letter which the US government said was written by al-Qaida's No. 2 man to its leader in Iraq outlines a four-stage plan for global jihad: Expel US forces from Iraq, establish an Islamic authority, take the battle to Iraq's secular neighbors, Syria and Egypt, and then "clash with Israel because Israel was established only to challenge any new Islamic entity." While the legitimacy of the letter remains in question, Dr. Reuven Paz, an expert on global jihad, said that the four-step plan follows "the real strategy of al-Qaida." "The path to liberate Jerusalem passes through the liberation of Cairo and Damascus, because for them Assad and Mubarak are infidels," said Paz, who is the director of PRISM the Project for Research of Islamist Movements at the Interdisciplinary Center in Herzliya. "In their view Israel can be defeated by a real jihad of a real Islamic state," he continued. "So first they have to expel the United States from the region, then fight the Arab governments and establish a true Islamic state, and then to fight Israel." The letter was purportedly intercepted in Iraq in July, but only released this month for security reasons, the US said. However, in a posting on an Islamic Web site on Wednesday, Abu Maysara, al-Qaida's spokesman in Iraq, said the letter was fabricated. "We in al-Qaida declare that there is no truth to these claims, and they are baseless, except in the imagination of the politicians of the Black [White] House," according to the statement on the al-Hesba Web site, known for its al-Qaida material. Neither the letter nor the statement could be authenticated. Paz also expressed his doubts about the authenticity of the letter. "One very strange issue in this letter is that it twice mentions Israel," said Paz. "These groups never say Israel by name. They would say the Jewish entity or the Zionist entity. This is the first thing that made me think it's part of a psychological war." Nevertheless, said Paz, fears of al-Qaida's presence on Israel's borders are real. "In Israel they have no presence so far, although they may have supporters in Gaza," he said. "But they are definitely trying to infiltrate Sinai." The letter is striking because its author, whom the US said is Ayman Zawahiri, criticizes Abu Musab al-Zarqawi for attacks against Muslims which could cause the loss of what he calls a "media battle" for the "hearts and minds" of Muslims. "I say to you, we are in a battle, and that more than half of this battle is taking place in the battlefield of the media," Zawahiri writes. "The Muslim populace who love and support you will never find palatable ... the scenes of slaughtering the hostages," he warns. The letter's release follows public criticism of Zarqawi's Jordanian mentor for killing Muslims and criticism by an important Islamic cleric in London for the London bombings. "It looks to me that the Americans are using the debate of these men about the strategy in Iraq to raise more criticism of Zarqawi's actions in Iraq," said Paz. "But then who knows?" He added that the style of Arabic is not of an Egyptian Islamist. "It was written by an Arab for sure," said Paz, "even if it was written by the Americans. It could be a joint operation with some Arab governments. But we can't know."