* Ishaq killed as Assad expands control around Damascus
* Mleiha, scene of heavy fighting, lies on airport road
* Rebels seize town in Hama province, kill 34 - monitor (Adds fighting in Hama province)
BEIRUT, May 18 (Reuters) - Syria's air defence chief was killed during an offensive by President Bashar al-Assad's forces against rebels east of Damascus, Islamist rebels and a monitoring group said.
They said General Hussein Ishaq died on Sunday from wounds suffered on Saturday during the assault by Assad's forces on the town of Mleiha which appears aimed at expanding the president's control around the capital before a June 3 election.
The air defence forces which have a large base in Mleiha and are responsible for defending against air attacks, have played little part in the war with rebels who have no air power.
However, Ishaq is one of the most senior military officials to be killed in three years of conflict.
The last high-ranking casualty was Hilal al-Assad, a cousin of the president and regional head of the National Defence Force militia, who was killed two months ago in the Mediterranean province of Latakia.
"We announce good news to the Islamic nation, of the killing of one of the leaders of unbelief, General Hussein Yaqoub Ishaq, head of the Air Defence Administration in Mleiha," the Islamic Front said in a statement.
The Syrian Observatory for Human Rights, a Britain-based monitoring group, also reported Ishaq's death in Mleiha, which is close to the road linking central Damascus to the international airport.
Mleiha lies on the edge of the eastern Ghouta region - a mix of farmland and small towns which have formed a base for rebel fighters but which have been surrounded by Assad's forces for more than a year.
The army, backed by Shi'ite fighters from Iraq and Lebanon's Hezbollah group, has pushed back the rebels around Damascus and consolidated Assad's grip over central Syria, including the Lebanese border the country's third-largest city, Homs.
State media made no mention of Ishaq's death but pro-Assad Internet sites said he was "martyred" in Mleiha.
REBELS SEIZE HAMA TOWN
North of Damascus, rebels killed 34 pro-Assad fighters when they attacked an army post near the town of Tel Malah in Hama province on Sunday, the Observatory said.
Video footage released by the rebels showed the building - a school which they said the army had commandeered as a base - as well a captured armoured personnel carrier and a tank.
The area has changed hands several times during Syria's protracted conflict, and the rebels said it was the third time they had taken control there.
The town of Tel Malah lies on a road linking two Christian towns in Hama province and is also close to several Alawite villages.
Assad's family is from Syria's Alawite minority, who mostly support the president, and many Christians also back him, fearing the increasingly radicalised Sunni Muslim rebels.
The rebels who took over Tel Malah included fighters from the Nusra Front - al Qaeda's official branch in Syria - the Islamic Front.
More than 150,000 people have been killed in Syria's civil war, which erupted after Assad responded with force to protests against his rule three years ago.
After clawing back territory in the centre of the country Assad is now preparing for a presidential election which is widely expected to extend his 14-year rule for another seven-year term. (Reporting by Dominic Evans; Editing by Alison Williams and Sophie Hares)