On Tuesday, British Prime Minister David Cameron floated the idea of granting Assad safe passage from the country, saying it “could be arranged,” although he wanted him to face international justice.

Assad, who has made only rare public statements in recent months, also warned against a foreign intervention in Syria’s escalating conflict, saying such a move would have global consequences and shake regional stability.

“We are the last stronghold of secularism and stability in the region... it will have a domino effect that will affect the world from the Atlantic to the Pacific,” the transcript said.

In a separate video extract of the interview, Assad added: “The price of this invasion, if it happens, is going to be big, more than the whole world can afford.”

Many in Syria’s opposition, including rebels waging fierce battles with pro-regime forces, have urged world powers to intervene to stop the escalating bloodshed.

Fighting continued around the country on Thursday, as the Red Cross said it was struggling to cope with Syria’s worsening humanitarian crisis.

Heavy clashes for control of the mainly Kurdish northeastern town of Ras al-Ain on the Turkish border killed 16 soldiers and 10 rebels, the Syrian Observatory for Human Rights said.

Turkish media reported that two Turks were wounded by bullets fired from across the border amid the fighting.

Fresh violence also broke out in the southern Damascus neighbourhood of Qadam and in Mazzeh in the west of the capital, said the Britain-based Observatory, which relies on a network of activists and medics on the ground.

It said at least 86 people were killed on Thursday, including 38 soldiers.

The Observatory says more than 37,000 people have died since the uprising against Assad erupted in March last year, first as a protest movement and then an armed rebellion after the regime cracked down on demonstrations.

In Geneva, International Committee of the Red Cross President Peter Maurer said the aid group was finding it difficult to manage a crisis that has also forced hundreds of thousands or people from their homes.

“The humanitarian situation is getting worse despite the scope of the operation increasing,” he told reporters. “We can’t cope with the worsening of the situation.”

In Qatar, meanwhile, Syrians from a wide spectrum of opposition to Assad were meeting to begin hammering out a government-in-waiting world powers will accept as credible and representative.

Ahmed Ben Helli, deputy head of the Arab League - which with Qatar is brokering the meeting - told reporters that delegates had been urged to overcome the sharp divides that have dogged their efforts to unseat Assad.

The main opposition umbrella group, the Syrian National Council, earlier elected a new 40-member general secretariat with Islamists, including at least five Muslim Brotherhood members, accounting for about a third.

Despite calls from Washington for the SNC to be more representative, the some 400 members failed to elect a single woman or any Alawite to the leadership.

SNC officials said four members representing women and minorities, including a Christian and an Alawite, would now be added to the secretariat, which on Friday will elect 11 members to appoint a successor to outgoing president Abdel Basset Sayda.

With the violence in Syria often spilling over the country’s borders, neighbouring Turkey confirmed it was in talks with Nato about the possible deployment of Patriot surface-to-air missiles on its soil, while insisting it would be purely defensive.

“It is only natural for us to take any measure for defence reasons,” President Abdullah Gul told reporters on Thursday, adding that it was “out of the question for Turkey to start a war with Syria.”

Media reports have suggested the missiles could be deployed on the border to create a partial no-fly zone and allow for the establishment of safe havens inside Syria.