* Arabs in disarray over Iran, Syria, Egypt
* Syria's war echoes region's sectarian strains
* Most Arab leaders wary of fledgling US-Iranian thaw (Adds Iraqi foreign minister, paragraphs 7-9)
By Sami Aboudi and Sylvia Westall
DUBAI/KUWAIT, March 23 (Reuters) - Rifts over foreign policy will likely make it harder for Arab leaders meeting at a summit this week to forge a common stand on regional challenges, including what many of them see as a threat from Iranian-U.S. rapprochement.
And while the Arab League meeting may agree more humanitarian action in response to Syria's war, any communique calling for the removal of President Bashar al-Assad will not reflect divergent views behind the scenes about the Syrian leader's handling of the conflict.
Syria and Iran are not the only points of contention at the annual summit, scheduled to take place in Kuwait on March 25-26.
The meeting follows an unprecedented row among members of the Gulf Cooperation Council (GCC) alliance of Gulf Arab states over support for Egypt's Muslim Brotherhood and a verbal spat between Iraq and Saudi Arabia over violence in Iraq's Anbar province.
"No summit has been without differences, but this one is full of differences. It is distinguished by the intensity of these disputes which puts an extra burden on the host country," said Ebtisam al-Qitbi, a professor of political science at the Emirates University in the United Arab Emirates.
"It will definitely make it more difficult to focus on coming out with adequate resolutions, not to mention an agreement on anything," she added.
Ahead of the summit, Iraq's Foreign Minister Hoshiyar Zebari said there had been no tensions at a meeting of his Arab counterparts in preparation for discussions later this week.
"The Kuwaiti host in fact has smoothed relations. There were no tensions between the delegates who were present," he told reporters in Kuwait.
A decision by Saudi Arabia, the United Arab Emirates and Bahrain earlier this month to withdraw their ambassadors from Qatar was not discussed at the meeting, he said.
Arab summits have long been dominated by the Israeli-Palestinian conflict, a topic on which most Arab states share a common view. But "Arab Spring" uprisings that began in 2011 have polarised the region.
Syria's war echoes strains between Sunni Muslims, notably in the Gulf, and Shi'ites in Iraq, Lebanon and Iran, whose faith is related to that of Assad's Alawite minority.
"STAND BY THE SYRIAN PEOPLE"
"There is a desperate need to clear the Arab atmosphere and to benefit from convening the summit," Arab League Secretary-General Nabil Elaraby said in remarks carried by Egyptian media last week.
In separate remarks, Elaraby agreed at a news conference that the summit's decisions would be affected by "differences".
Syrian opposition leaders have been lobbying the 22-member League of Arab States to give them Syria's seat on the pan-Arab body, and to push Arab states to approve the delivery of military hardware to them to boost their fight to bolster Assad.
Elaraby said in Kuwait that Syria's Arab League seat would remain vacant. A senior Kuwaiti official, however, said that the head of the opposition Syrian National Coalition, Ahmed al-Jarba, would deliver a speech at the summit.
"The Arab summit is required to stand by the Syrian people in its great tragedy, not with words only but with material, financial, political and military backing," Saudi Arabia's Okaz newspaper quoted National Coalition member Mohammed al-Sarmini as saying.
But Syria's Arab allies, including Iraq, Algeria and Lebanon, oppose any such support for the rebels. They point out that Islamists, including groups linked to al Qaeda, are the most potent force in the armed opposition.
Most Gulf Arab states, wary of Iranian influence among Shi'ite co-religionists in Bahrain, eastern Saudi Arabia, Kuwait and Iraq, want the summit to send a strong message to Iran to stop alleged meddling there. Iran denies any interference.
They also fret that their main ally, the United States, participating in talks about Iran's disputed nuclear programme, may one day restore full ties with Tehran three decades after they were cut in a crisis over the taking of U.S. hostages.
"Gulf states see the main challenge coming from Iran's geo-political project," Qitbi said. "This project is getting strong and is trying to find cracks through which to penetrate the Arab wall."
The summit is also likely to be complicated by the political fragility of Egypt, the most populous Arab country: Cairo has been absorbed by its own internal problems since Egypt's army ousted President Mohamed Mursi and his Muslim Brotherhood group from power last year after mass protests against his rule.
The army takeover fuelled long-standing differences between Qatar, a Brotherhood ally, and Saudi Arabia and the United Arab Emirates, which both see the group as a potent political threat.
"I think the Kuwaitis are anxious to ensure the Arab League summit passes off smoothly and without major embarrassment," said Kristian Ulrichsen, a Gulf expert at the U.S.-based Baker Institute.
"The emir and his officials will be keen to prevent any escalation of the diplomatic row with Qatar and may use the summit to step up private efforts to mediate a solution." (Writing by Sami Aboudi; Editing by William Maclean and Sophie Hares)