Leaders of the Palestinian Islamist movement Hamas turned publicly against their long-time ally President Bashar al-Assad of Syria on Friday, endorsing the revolt aimed at overthrowing his dynastic rule.

The policy shift deprives Assad of one of his few remaining Sunni Muslim supporters in the Arab world and deepens his international isolation. It was announced in Hamas speeches at Friday prayers in Cairo and a rally in the Gaza Strip.

Hamas went public after nearly a year of equivocating as Assad's army, largely led by fellow members of the president's Alawite sect, has crushed mainly Sunni protesters and rebels.

In a Middle East split along sectarian lines between Shi'ite and Sunni Islam, the public abandonment of Assad casts immediate questions over Hamas's future ties with its principal backer Iran, which has stuck by its ally Assad, as well as with Iran's fellow Shi'ite allies in Lebanon's Hezbollah movement.

'I salute all the nations of the Arab Spring and I salute the heroic people of Syria who are striving for freedom, democracy and reform,' Hamas leader Ismail Haniyeh, visiting Egypt from the Gaza Strip, told thousands of Friday worshippers at Cairo's al-Azhar mosque.

'We are marching towards Syria, with millions of martyrs,' chanted worshippers at al-Azhar, home to one of the Sunni world's highest seats of learning.

 'No Hezbollah and no Iran. The Syrian revolution is an Arab revolution.'

Contemporary political rivalries have exacerbated tensions that date back centuries between Sunnis - the vast majority of Arabs - and Shi'ites, who form substantial Arab populations, notably in Lebanon and Iraq, and who dominate in non-Arab Iran.

Hamas and Hezbollah, confronting Israel on its southwestern and northern borders, have long had a strategic alliance against the Jewish state, despite opposing positions on the sectarian divide. Both have fought wars with Israel in the past six years.

But as the Sunni-Shi'ite split in the Middle East deepens, Hamas appears to have cast its lot with the powerful, Egypt-based Sunni Islamists of the Muslim Brotherhood, whose star has been in the ascendant since the Arab Spring revolts last year.

'This is considered a big step in the direction of cutting ties with Syria,' said Hany al-Masri, a Palestinian political commentator. Damascus might now opt to formally expel Hamas's exile headquarters from Syria, he told Reuters.

Banned by deposed Egyptian leader Hosni Mubarak, the Muslim Brotherhood has moved to the centre of public life. It is the ideological parent of Hamas, which was founded 25 years ago among the Palestinians, the majority of whom are Sunni Muslims.-Reuters