AMMAN — Syrian rebels captured an army base in the eastern oil province of Deir Al-Zor Thursday, striking another blow against President Bashar Al-Assad's military and further weakening his control in the strategic region bordering Iraq. The capture of the artillery base on the outskirts of Mayadeen, a town on the Euphrates river near some of Syria's main oilfields, follows rebel takeovers of military installations in the north and center of the country this week. Recent rebel momentum shows the increasing potency of the mainly Sunni Muslim fighters trying to topple Assad. But insurgents have often had to retreat quickly after making advances to avoid strikes by the president's air force. “The Mayadeen military base fell at 8.30 a.m. (0630 GMT),” Abu Laila, an official in the Military Revolutionary Council in the province, told Reuters. He said 44 rebel fighters had been killed in the siege of the base. “The whole countryside, from the Iraqi border and along the Euphrates to the city of Deir Al-Zor, is now under rebel control.” Another opposition source in contact with rebels confirmed that the base, 42 km southeast of the city of Deir Al-Zor, had fallen. Activists say 38,000 people have been killed in the 20-month-old uprising. Hundreds of thousands have fled the country and 2.5 million are displaced, aid groups say. The capture of the Mayadeen base leaves Assad controlling just three major army bases in Deir Al-Zor province, said Sheikh Nawaf Al-Bashir, a local tribal leader. He said rebels now held the main road to Iraq, from the outskirts of the city to the border crossing of Albu Kamal. Last week rebels seized a military airport 80 km southeast of Mayadeen, on the Iraqi border. Rebels also stormed a special forces base near Aleppo, Syria's commercial hub, and an air defense position in the southern suburbs of Damascus. Rebels are gaining strength in Damascus, partly because they are being joined by fighters from outlying regions. While Assad's forces control main road junctions there have been guerrilla attacks in the last few days near Damascus Airport and rebels have expanded control of the mixed urban and farmland regions around Damascus the capital. Army shells struck a building next to Aleppo's Dar Al-Shifaa hospital on Wednesday, one of the main rebel medical centers, killing 15 people. Most of the dead were fighters but a doctor and three children also died, it said. — Reuters