The sectarian bloodbath in Syria is such a threat to regional security that a victory for Bashar al-Assad could be the best outcome to hope for, a former CIA chief said.

The sectarian bloodbath in Syria is such a threat to regional security that a victory for Bashar al-Assad could be the best outcome to hope for, a former CIA chief said.

Michael Hayden, the retired US Air Force general who until 2009 was head of the Central Intelligence Agency, said a rebel win was not one of the three possible outcomes he foresees for the conflict.

"Option three is Assad wins," Hayden told the annual Jamestown Foundation conference of terror experts.

"And I must tell you at the moment, I'm kind of trending toward option three as the best out of three very, very ugly possible outcomes," he said.

Hayden deemed that the most likely outcome would be the "dissolution of Syria" and the end of a single state within the borders defined by a 1916 treaty between the French and British empires.

"It means the end of the Sykes-Picot (Agreement), it sets in motion the dissolution of all the artificial states created after World War I," he said.

The British diplomat Mark Sykes and a French counterpart Francois Georges Picot divided the Middle East into zones of influence that later served as the frontiers of independent Arab states.

A breakdown in the century-old settlement could spread chaos in Lebanon, Jordan and Iraq, Hayden warned.

"I greatly fear the dissolution of the state. A de facto dissolution of Sykes-Picot," Hayden said.

"And now we have a new ungoverned space, at the crossroads of the civilization."

"The dominant story going on in Syria is a fundamentalist takeover of a significant part of the Middle East geography, the explosion of the Syrian state and of the Levant as we know it."