CAIRO (Reuters) - A congress of leading Sunni Muslim clerics issued a call to holy war on Thursday against the Damascus government and its Shi’ite allies, hardening sectarian confrontation across the Middle East over the Syrian conflict.

Alarmed by reverses for the mainly Sunni rebels since the Iranian-backed Lebanese militia Hezbollah threw its full weight behind President Bashar al-Assad last month, Sunni religious authorities have stepped up rhetoric that could fuel a wider regional conflict and communal bloodshed in Syria and elsewhere.

Concluding a conference in Cairo at which more than 70 Sunni scholarly organizations were represented, a leading Egyptian preacher made a televised statement accusing the rebels’ enemies of waging “war on Islam”. He urged the faithful to send money and arms to Syria and pursue “all forms of jihad”.

Among those present was Youssef al-Qaradawi, a renowned, Qatari-based Egyptian preacher close to Cairo’s ruling Muslim Brotherhood, but the statement did not explicitly repeat a call by him two weeks ago for Sunnis to go and fight in Syria.

The number and prominence of those represented, however, made this a significant reinforcement of sectarian rhetoric.

“Jihad is necessary for the victory of our brothers in Syria - jihad with mind, money, weapons; all forms of jihad,” said preacher Mohamed Hassan, reading from the statement.

It called for “support, whatever will save the Syrian people from the grip of murder and crime by the sectarian regime”.

“What is happening to our brothers on Syrian soil, in terms of violence stemming from the Iranian regime, Hezbollah and its sectarian allies, counts as a declaration of war on Islam and the Muslim community in general,” Hassan said.

Shi’ite, non-Arab Iran has long sponsored the Assad administration, which is dominated by the president’s fellow Alawites, a religious community that is an offshoot of Shi’ite Islam. Sunni powers, including Saudi Arabia, Qatar and Egypt, as well as Western states, have taken up the rebel cause.

The congress urged governments not to cooperate with not only Iran but also with Russia and China, which have blocked U.N. resolutions aimed at sanctioning Assad.

It urged the rebels, mostly drawn from Syria’s majority Sunnis, to overcome their internal differences. And it criticized those governments which have labeled some Islamist rebels as “terrorists”, a factor which the United States and others have used to justify their reluctance to arm the rebels.

The Sunni Islamist administration in Egypt, which rose to power in the same movement of Arab revolt that started the war in Syria two years ago, has condemned Assad and Hezbollah but has stopped short of urging Egyptians to join the rebel side.

A senior aide to President Mohamed Mursi said on Thursday, however, that Cairo was not preventing Egyptians, by far the most populous Arab nation, from going to Syria if they wished.

“The freedom of travel ... is open for all Egyptians,” Khaled al-Qazzaz, Mursi’s foreign affairs adviser, told a news briefing. “But we did not call for Egyptians to go and fight in Syria.”