The latest flurry of predictions by Western officials, and even by a top Russian diplomat, reflect the fact that the rebels are advancing on the ground but not that the regime is on the verge of collapse, analysts say.

"It will fall in a coup, by foreign intervention or a massive expansion of logistical support to the rebels by foreign countries," said Barah Mikail, a researcher at the Spanish Institute for Geopolitics (FRIDE).

Mikail's advice was not to "overestimate" the predictions.

"The regime's military and institutional structure remains intact, even if it has suffered some shocks," as with last week's attack in Damascus in which the interior minister was wounded.

Several top foreign officials have sounded the death knell of Assad's regime, including Nato chief Anders Fogh Rasmussen. "It is only a question of time," he said.

French President Francois Hollande has called on the international community to "make Assad leave as quickly as possible", while the US State Department said the regime had become "more and more desperate".

Russian Deputy Foreign Minister Mikhail Bogdanov said the Syrian regime was "losing more and more control over a large part of the country's territory", before his government quickly distanced itself from his assessment.

Rami Abdel Rahman, head of the Britain-based Syrian Observatory for Human Rights, said the growing predictions could signal that world powers are closing ranks on the 21-month conflict.

"Either this is the beginning of an international consensus to end the regime, or Western countries are in contact with a large and influential group in the army that may turn on Assad," he said.

"Or they are ratcheting up the pressure for Assad to exit to avert a total disintegration of the state," he said.

But Abdel Rahman, whose organisation documents the conflict through a large network of activists and medics across Syria, said the army was still very strong.

"Despite losses in its ranks and defections, it is still capable of protecting a large portion of territory from Damascus to the coast," heartland of the Alawite minority to which the president belongs.

But the military-security apparatus has significantly eroded, as exemplified by multiple car bombings in Damascus.

"It is certain that the rebels have made advances and are acting more boldly, but for the moment the army maintains overall cohesion and defends the country's major cities," said a Western military expert in Beirut.

"Despite the desertions and deaths, the army still has 200 000 people, of all religious faiths, and has not yet engaged all of its units on the battlefield … It believes it has a mission," the expert said.

"It felt uncomfortable at the beginning when [soldiers were] asked to fire on unarmed civilians, but there is no sympathy at all now that the revolt has transformed into an insurgency," he added.

On the diplomatic front, however, Assad's foes in the opposition National Coalition have gained widespread international recognition as the legitimate representative of the Syrian people.

Only three key allies remain: Iran and UN Security Council veto-wielding members China and Russia which have blocked all resolutions condemning the regime.

A day after Bogdanov's comments, Russian foreign ministry spokesperson Alexander Lukashevich said: "We have never changed our position [on Syria] and we never will."

But a Syria specialist, speaking on condition of anonymity because of frequent visits to Damascus, said: "These statements prove that earnest negotiations have begun between the United States and Russia to find a solution to the crisis.

"But to repeatedly announce that the regime will fall imminently can be counter-productive because if this is not the case in the coming days or weeks, the regime will claim that it is strong enough not to make concessions." – AFP