AMMAN (Reuters) - The most senior commander to abandon the Syrian military during a 10-month uprising against President Bashar al-Assad said desertions were wearing down the army but rebels could take more than a year to topple him.
General Mostafa Ahmad al-Sheikh told Reuters that up to 20,000 soldiers, mostly majority Sunni Muslims, have deserted despite "iron controls" and large swathes of land are regularly falling into rebel hands before loyalist forces mount operations to retake them.
However the revolt is likely to take longer than revolutions that toppled the autocratic rulers of Libya, Egypt and Tunisia because Assad retains the loyalty of highly trained and well equipped forces from his minority Alawite sect, he said.
"If we get 25,000 to 30,000 deserters mounting guerrilla warfare in small groups of six or seven it is enough to exhaust the army in a year to a year-and-a-half, even if they are armed only with rocket-propelled grenades and light weapons," he said in the telephone interview from south Turkey on Thursday.
Sheikh said most deserting soldiers have not taken up arms against pro-Assad forces and their primary concern has been to evade capture by secret police units in charge of stifling dissent within the military.
He said he had started helping to reorganize the Syrian Free Army, an umbrella group of defectors that formed several months ago under which deserters are loosely based.
"The Free Syrian Army needs to remain under control for fear that the regime may suddenly collapse," he said, advising rebels to stick to protecting protesters until they are molded into a more effective force.
Army deserters have carried out a wave of attacks on military and security targets, raising the prospect of the mainly peaceful protests against Assad being eclipsed by an insurgency that could tip Syria towards civil war.
Sheikh estimated the size of the Syrian army, on which Assad has relied to try and put down the revolt, at 280,000 soldiers, including conscripts.
"The desertions have been locally based and in small groups. Mass defections will occur when there is an open horizon and when the soldier feels there is an international decision to bring down the regime," Sheikh said.
"Safe havens will help. If they are set up, whole units will defect and the regime will fall much quicker," he said, referring to a possible buffer zone on the border with Turkey.
Syrian soldiers were "under surveillance and iron constraints" and knew that deserting would trigger revenge against family members, he said, but desertions continued nonetheless.
"Every time now they storm cities or towns, Sunnis among the attacking forces defect," said Sheikh, who is from the northwestern province of Idlib.
Sheikh said he decided to desert after he was told that a security police unit gang-raped the 20-year-old bride of a young anti-Assad activist in the countryside near Hama, and after security police sexually abused and filmed students who had rallied in the main commercial hub of Aleppo, whose influential merchants support Assad or have taken no side in the conflict.
Sheikh's assertions could not be verified. Syrian authorities have denied reports of abuses and say they are fighting foreign-backed Islamists who have killed 2,000 soldiers and police.
Sheikh fled his post in the northern command among ground forces based in Aleppo this month and crossed to neighboring Turkey, becoming the highest ranking officer to desert.
He said he was still adjusting to freedom.
"We have lived 40 years in repression. The regime has separated brother from brother, along with murder and torture on an unimaginable scale. Syrians still need to believe that they are human beings," he said, referring to four decades of rule by Assad and his father, who took power in a 1970 coup.
Editing by Dominic Evans and Mark Heinrich