GAZA, Feb 13 (Reuters) - The two top leaders of the Islamist Palestinian group Hamas failed at secret talks in Qatar on Sunday to resolve an internal crisis over a reconciliation pact with the rival Fatah movement of President Mahmoud Abbas, a diplomat in the region said.

The first open leadership split in the 25-year history of Hamas -- the militant, Iranian-funded organisation which opposes a peace treaty with Israel -- arose over how far it should go in closing ranks with Fatah, the Palestinian mainstream group.

"Khaled Meshaal and Ismail Haniyeh met last night in Qatar to discuss the dispute in Hamas over the Doha agreement," the diplomat told Reuters on Monday, naming the two main figures in the organisation.

Meshaal has recently quit his longtime Damascus headquarters, politically embarrassed by Syrian President Bashar al-Assad's bloody crackdown on an uprising waged by fellow Sunni Muslims. Haniyeh flew to Qatar from Iran, Syria's ally and a sworn enemy of Israel and its Western supporters, which was displeased by Meshaal's refusal to stay and support Assad.

The two Islamist leaders are not, however, on opposing sides of the internal dispute in Hamas, but are trying to resolve differences in its collegial leadership between Meshaal and Gaza-based group leaders close to Haniyeh, analysts say.

"The crisis persists," the diplomat told Reuters after the Qatar meeting. He asked not to be identified.

Hamas and Fatah have been enemies since their armed factions fought in Gaza in 2007, splitting the Palestinian national movement in two. Abbas, backed by the West, is committed to seeking peace with Israel. Hamas, backed by Iran and its Arab ally Syria, is not.

Both movements have been saying for over a year that it is high time to end their divisive and damaging rivalry. But so far they have failed to make a deal that will stick.

Some in the top ranks of Hamas believe that with Middle East peace talks now on the rocks, the recent rise of Islamist movements in the Arab world gives them more leverage over Western-backed Abbas than they have ever had.

But Hamas leader-in-exile Meshaal, with close ties to Egypt's Muslim Brotherhood, sees it as a time for accommodation rather than confrontation, together with subtle policy adjustments to end Hamas's isolation.

Meshaal and Abbas signed a pact in the Gulf state of Qatar last week, according to which Abbas would lead an interim government of technocrats with the task of preparing for overdue presidential and parliamentary elections later this year.

Haniyeh, the Hamas leader in Gaza, backed the deal but other senior Hamas figures in Gaza were vocally opposed, pitching the movement into a rare open dispute.

Haniyeh flew to Qatar from Iran, where he met leaders of the Islamist Republic. Relations have soured in past year over the lack of public support from Hamas for their common ally Assad in his handling of Syria's uprising.

A statement from Haniyeh said Iran reaffirmed its support for the Palestinian people "and by all means to reinforce the steadfastness and resistance against the (Israeli) occupation."

Israel says Tehran supplies Hamas with rockets and guns.

It was unclear, however, if Iran would resume funding for Hamas, which diplomats say has been suspended since August 2011.

SYRIAN EMBARRASSMENT

The Qatar deal, which would make Abbas president and prime minister at the same time for the duration of the interim government, angered those in Gaza who feel Meshaal made too big a concession to the Palestinian leader in the Israeli-occupied West Bank without obtaining their approval.

Under Hamas rule, Gaza effectively runs its own affairs, ignoring anything from the West Bank that it does not like.

Meshaal has until recently been based in the Syrian capital, Damascus. But in view of the crisis there, in which fellow Sunni Muslims are being killed by government forces, he has been politically embarrassed and is now seeking new headquarters.

Haniyeh is top man in Israeli-blockaded Gaza, heading a more disparate group of senior figures with divergent views.

The Hamas-Fatah pact aims to heal five years of political division since Hamas gunmen seized control of Gaza after a brief civil war and ejected Fatah from the enclave, splitting the Palestinians politically, on top of geographically.

Analysts say Hamas leaders in Gaza believe there is no need for concessions at this time to Western-backed Abbas, whose foreign-funded Palestinian Authority holds sway in the Israeli-occupied West Bank, separated from Gaza by Israeli territory.

Hamas formally opposes a permanent peace with the Jewish state and refuses to recognise it. Israel dismisses suggestions that the group might agree to a long-term truce, and has warned Abbas that an eventual Palestinian government which included Hamas would mean closing the door to peace talks.

Hamas is shunned by the United Nations and the West as a terrorist organisation and will remain so unless it recognises Israel, renounces violence and endorses all previous agreements made between Israel and the Palestine Liberation Organisation, of which it is not a member.

Analysts say there is no indication whatever that Hamas is getting ready to take such a radical step, but they are intrigued by Meshaal's softer tone in recent months, and the suspicions it has aroused among Hamas hardliners.

"TOUGH DILEMMA"

Mahmoud Al-Zahar, a senior Hamas figure in Gaza seen as a hardliner by Fatah, described Meshaal's agreement with Abbas as a "mistake". Zahar clashed with Meshaal late last year when the exiled leader advocated giving Abbas more time to pursue his peacemaking with Israel.

"Gaza leaders believe they have the jurisdiction over Gaza where any agreement has to be implemented, while Meshaal believes he did what is best to end political rifts," said a second diplomat in the region.

"The group for the first time in its history finds itself in a real and tough dilemma," he said. "The Doha agreement needs a miracle to be implemented. The crack it caused in the integrity of Hamas is one that will be difficult to overcome."

Hamas sources say some officials are demanding that the group should have key portfolios in the proposed interim government if Abbas is to be prime minister as well as president. That would violate the whole point of the interim arrangement, which is that the government must be made up of political independents, not men from factions.