By Dominic Evans

BEIRUT (Reuters) - Syrian air force jets bombarded the eastern city of Deir al-Zor on Friday after heavy overnight clashes and the killing of one of President Bashar al-Assad's top military intelligence officers, activists said.

General Jama'a Jama'a was shot dead on Thursday by snipers in the midst of a battle with rebels including forces linked to al Qaeda, the Syrian Observatory for Human Rights said.

His death, celebrated by rebels and opposition activists, marked a significant setback for Assad's bid to retain a hold over the city, capital of the eastern oil-producing province.

A death notice published on Facebook said Jama'a's body was being flown back for burial on Friday in his home village of Zama in the mountains overlooking the Mediterranean - the heartland of Assad's Alawite sect.

Syria's 2-1/2-year-old uprising began with peaceful protests but has descended into a brutal civil war with sectarian dimensions. Syria's Sunni Muslim majority has largely joined the revolt against four decades of Assad family rule. Minority sects such as the Alawites, an offshoot of Shi'ite Islam, have largely stood behind the president.

Jama'a, 59, had served as Syria's top military intelligence officer in Lebanon until Damascus withdrew its forces from its smaller neighbor under intense international pressure in 2005.

The withdrawal followed the February 14, 2005 assassination of Lebanon's former prime minister Rafik al-Hariri, a killing widely blamed at the time on Syria, and for which Jama'a himself was investigated by a United Nations team.

Jama'a was then appointed chief of military intelligence in Deir al-Zor, a prominent and sensitive position because of the flow of Sunni militants across the border into Iraq where insurgents were fighting U.S. and Iraqi Shi'ite forces.

In August 2011, five months after protests first erupted against Assad, the European Union imposed sanctions on Jama'a for his role in "repression and violence against the civilian population".

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DOZENS KILLED

Activists say dozens of rebels and pro-Assad forces have been killed this week in heavy fighting around Deir al-Zor.

The Observatory reported clashes overnight in several districts of the city and said rebels from the al Qaeda-linked Nusra Front executed 10 soldiers they captured in the Rashidiyah district, where Jama'a was killed on Thursday.

While rebels had made progress and launched an attack on the nearby military airport, they were unlikely to achieve a speedy and complete victory in the strategic oil region which borders Iraq, the Observatory's Rami Abdulrahman said.

Although much of Deir al-Zor province is under rebel control, some tribes remain loyal to Assad and control of the city itself is shared between rebels and loyalists, he said.

Syria's civil war has killed more than 100,000 people and divided the Middle East between Sunni Gulf states and Turkey which mostly support the rebels, and Shi'ite Iran and Hezbollah which have backed Assad.

International efforts are growing to convene peace talks in Geneva next month, encouraged by rare agreement among global powers over the elimination of Syria's chemical weapons after sarin gas attacks near Damascus in August.

But the United States and Russia, responding to Syria's announcement that the talks would go ahead in Geneva on November 23-24, said on Thursday that no date had yet been set.

The international envoy for Syria, Lakhdar Brahimi, is due to hold talks in the Middle East next week to try to prepare for the negotiations, his spokeswoman Khawla Mattar said.

Mattar said Brahimi would start his tour in Cairo on Saturday, meeting Egypt's foreign minister. Iran and Syria are expected to be among the stops on Brahimi's itinerary.

While Brahimi is in the Middle East, Assad's international opponents will gather in London on Tuesday. The office of French Foreign Minister Laurent Fabius said he will travel to Britain for the meeting, which will be attended by U.S. Secretary of State John Kerry.

Even if the long-delayed Geneva talks do go ahead there is little prospect of forging a political deal on which Assad and his foes could agree.

POLITICAL TRANSITION

George Sabra, head of the Syrian National Council which is a prominent party in Syria's broad opposition coalition, said on Friday that Assad must step down as a precondition for the talks in Switzerland on political transition in Syria.

"We want an announcement in advance that Bashar al-Assad and his ruling clique ... form no part of the political life in Syria in the transitional stage and in future," he told Al-Arabiya Television. "The transitional body that results from the meeting should have full powers including those of the presidency."

Assad has said he will not step down before presidential elections next year in which he may seek a third term. He has ruled out a ceasefire with rebels he dismisses as terrorists and says there can be no talks with any opposition figures who support foreign military or political intervention in Syria.

Chemical weapons experts said on Friday they had visited 14 out of around 20 sites they are due to inspect in the early stages of their mission to oversee elimination of an arsenal believed to contain 1,000 tons of agents and precursors.

The Organisation for the Prohibition of Chemical Weapons says it is confident that it can meet deadlines for the destruction of the chemical stockpiles, although it still faces major challenges.

At least one site linked to Syria's chemical weapons program - near the northern town of Safira - is close to ongoing battles between rebels and Assad's forces.

Malik Ellahi, special adviser to the OPCW's director Ahmet Uzumcu, said discussions were being held to gain access to sites in sensitive locations.

The British-based Observatory, an anti-Assad group which monitors the conflict through medical and military sources in Syria, said 12 Kurds were killed in bombardment by Assad's forces of Tel Arn village, about 4 miles north of Safira.

It said 21 people had died in the village, which is under the control of the al Qaeda-linked Islamic State in Iraq and the Levant, in the last 24 hours.

South of Safira, at least 20 Syrian troops and seven rebel fighters were killed in a dawn attack by rebels on an air defense base. There have been regular clashes in the region in recent weeks as Assad's forces have sought to open up a supply route from the south to Aleppo, bypassing the main north-south highway which is partly under rebel control.

(Additional reporting by Stephanie Nebehay in Geneva and Nick Vinocur in Paris; Editing by Giles Elgood)