AMMAN/ALEPPO - President Bashar al-Assad controls less than a third of Syria and his power is crumbling, his former prime minister said on Tuesday, in his first public appearance since he defected to the opposition this month. Riyad Hijab told a news conference in Jordan that the morale of Syrian authorities was low after grappling for 17 months to crush a popular uprising and an armed insurgency against Assad. "The regime is collapsing, spiritually and financially, as it escalates militarily," he said. "It no longer controls more than 30 percent of Syrian territory." Hijab, a Sunni Muslim, was not in Assad's inner circle. But as the most senior civilian official to defect, his flight after two months in the job looked embarrassing for the president. Hijab did not explain his estimate of the territory still controlled by Assad, whose military outnumbers and outguns the rebels fighting to overthrow him. The army is battling to regain control of Aleppo, Syria's biggest city, after retaking parts of Damascus that were seized by insurgents last month. Curbs on media access make it hard to know how much of Syria is in rebel hands, but most towns and cities along the country's backbone, a highway running from Aleppo in the north to Deraa in the south, have been swept up in the violence. Assad has also lost swathes of land on Syria's northern and eastern border. While the military focuses on Damascus and the business hub of Aleppo, rebels have slowly made gains in Syria's tribal heartland to the east, where a ferocious fight is under way for Deir al-Zor, capital of the country's main oil-producing region. Army gunners shell Deir al-Zor, an impoverished Sunni city near the Iraqi border, from fortified outposts in the desert.