Hamas leader Khaled Meshaal, who survived a 1997 Israeli assassination bid, has confirmed he wants to quit after eight years in the post, the Islamist movement said on Saturday.
"Political bureau chief Khaled Meshaal has notified Hamas's consultative council that he does not wish to be a candidate for the movement's future leadership," a statement said.
Senior Hamas figures have asked the Damascus-based Meshaal to reconsider, the statement said.
They urged him to leave it to the consultative council to decide "on the basis of the higher interests of the movement," stressing that it was "not a purely personal matter."
Meshaal, 55, will remain active in Hamas "in the service of the people, the movement and the Palestinian cause," the statement stressed.
The political bureau is Hamas's principal decision-making body and its members are elected by secret ballot by the much larger consultative council.
The next elections are expected to be held in July or August, Hamas sources said.
Among the leading candidates to replace Meshaal are his number two, Mussa Abu Marzuq, who also lives in exile; the leader of the Hamas government in Gaza, Ismail Haniya, and another prominent Gaza Hamas figure, Mahmud Zahar.
The Hamas confirmation that Meshaal wants to step down comes amid press reports of growing friction between the Damascus-based leadership-in-exile and the movement's Gaza wing, which has ruled the territory since ousting Fatah forces loyal to Palestinian president Mahmud Abbas in 2007.
A series of Meshaal-Abbas meetings in recent months in a bid to reconcile the two factions and unify their rival administrations has reportedly drawn criticism from some Gaza leaders.
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Last month, the two men agreed on a process that could pave the way for the Islamist group to join a reformed Palestine Liberation Organisation (PLO) and for long-delayed Palestinian elections across Gaza and the occupied West Bank.
Abbas's secular Fatah faction has accused Hamas leaders in Gaza of trying to sabotage the reconciliation moves and has called on Meshaal to rein them in.
"We know that there are forces of Hamas in Gaza who want neither reconciliation nor to give up their empire, their money or their influence," the secretary general of Fatah's revolutionary council, Amin Maqbul, said last week.
"There is a real threat to reconciliation if the exiled leadership of Hamas does not begin to put pressure on those inside to change the situation in Gaza and insist on the culture of national unity and reconciliation," he told Voice of Palestine radio.
But on Saturday, Haniya announced that Hamas has agreed to the return to the territory from Egypt of 80 Fatah members.
Hundreds of Fatah members within the Palestinian security services fled to neighbouring Egypt, most of them after the bloody clashes in June 2007 when Hamas seized control of the coastal territory.
Meshaal was propelled into the movement's top job after the Israeli assassination of Hamas spiritual leader and co-founder Sheikh Ahmed Yassin in Gaza in March 2004, and the killing of his immediate successor Abdel Aziz Rantissi a month later.
The exiled Hamas leader remains a top target but Israel has so far been unable to reach him in Damascus, where he is under the de facto protection of the Syrian regime.
In 1997, agents from Israel's Mossad intelligence service disguised as Canadian tourists bungled an attempt to assassinate him on a street in Amman by injecting him with poison, but they were captured by the Jordanian authorities.
Meshaal fell into a coma and a furious King Hussein demanded Israel hand over the antidote if it wanted the captured agents to be freed.
The episode compelled Benjamin Netanyahu, then as now Israeli prime minister, to release Yassin and 19 others from prison.