(Adds background, reaction)
By Suleiman Al-Khalidi
AMMAN, Oct 21 (Reuters) - One of the most senior rebel commanders in southern Syria was killed during clashes with government troops near the city of Deraa on the border with Jordan on Monday, insurgents said.
Yasser al-Aboud, a former Syrian army officer who defected in the early days of the revolt to join the Free Syrian Army, was leading an assault on army checkpoints in the town of Tafas, northwest of Deraa, they added.
Allies said he had planned some of the rebels' main assaults on government positions in recent months.
The Syrian army controls most of Deraa, the cradle of the 2-1/2-year uprising against President Bashar al-Assad, on a major route to Damascus, just 90 km (55 miles) to the south.
But rebels have gained territory in the city's old quarter and surrounding rural areas.
"The commander Aboud was martyred as he was leading a group of rebels against regime's forces," said Abu Hamza from the rebel Falujat Huaran brigade that was involved in the clashes.
Aboud was a founding member of the Western-backed Free Syrian Army's military council in southern Syria, which groups moderate brigades and has said it is worried about the growing role of Islamist insurgents in the conflict.
Fighters said Aboud had also played a major role in trying to unite fractious insurgent brigades and ease divisions that have worried international backers.
"He will be sorely missed because unlike many of the army defectors he played a major role in organising rebel ranks and achieving major gains," said one of his comrades, known as Abu Kutaiba, in charge of logistics in the military council.
Rebels close to Aboud say he lobbied Jordan to allow Saudi Arabia, which publicly supports arming the rebels, to send shipments of anti-tank and aircraft weapons through the tightly sealed border into southern Syria.
They said Aboud argued that lack of advanced weapons in hands of the moderate groups was helping their rivals among al Qaeda inspired groups operating in southern Syria to gain ground. (Reporting by Suleiman Al-Khalidi; Editing by Andrew Heavens)