Syria's main civilian opposition alliance will ask for an Arab military intervention if President Bashar al-Assad's regime continues its deadly crackdown on protesters, the group's leader said Monday.

The Syrian National Council, which held a conference in Tunis in a bid to close ranks and up the pressure on Assad after nine months of bloodshed, also warned that the regime's acceptance an Arab peace plan was a ploy.

Arab League chief Nabil al-Arabi said on Monday that an advance team of observers would head to Damascus within 72 hours, after Syria inked a deal to end nine months of bloodshed.

"Within two or three days, an advance team of observers headed by Arab League Assistant Secretary General Samir Seif al-Yazal, including security, legal and administrative observers, will be sent," Arabi told reporters.

Iran on Monday said it backed Syrian President Bashar al-Assad's decision to start implementing an Arab League plan to quell the violence in his country by finally letting in observers.

But Tehran suggested it was not entirely happy with the pressure Arab states had brought to bear on Damascus, with President Mahmoud Ahmadinejad saying their action towards Syria was "like a joke."

The Syrian regime organized a show of support on Monday as expectations rose that it was finally set to admit observers to monitor implementation of an Arab deal to end nine months of bloodshed.

Hundreds of supporters of President Bashar Assad gathered in Sabaa Bahrat Square in the city center chanting slogans in support of their beleaguered leader and against the sanctions ordered by the Arab League.

Syria finally gave its agreement Monday to an Arab observer mission to monitor a deal to end nine months of bloodshed, ending weeks of prevarication that had prompted the Arab League to adopt sanctions.

Syrian Deputy Foreign Minister Faisal al-Maqdad and Arab League Assistant Secretary General Ahmed Ben Helli inked the document at League headquarters in Cairo, an Agence France Presse correspondent reported.

Syria has released Syrian-American blogger Razan Ghazzawi on bail two weeks after her arrest as she was heading to Jordan to attend a conference on press freedoms, a media rights group said on Monday.

"Razan Ghazzawi was released from detention at 10:30 pm (2030 GMT) Sunday on bail of 15,000 Syrian pounds (around 300 dollars)," the Syrian Centre for Media and Free Expression said on its website.

The Arab League is "optimistic" that by Monday Syria will sign a proposal to send an observer mission to the unrest-hit country, the Omani minister responsible for foreign affairs said Sunday, as Qatar’s premier said "we have received information stating that he (Syrian President Bashar al-Assad) will sign the protocol."

"We'll see if it's true," Qatari Prime Minister and Foreign Minister Sheikh Hamad bin Jassem al-Thani, who chairs an Arab League taskforce on Syria, added.

Progressive Socialist Party leader Walid Jumblat reiterated on Sunday that he remains allied with Premier Najib Miqati and said he is keen on seeing Syria united.

During a gathering at the Shouaifat Municipality called for by the head of the Lebanese Democratic Party, Talal Arslan, Jumblat said: “I might have a (different) viewpoint in political affairs and this is legal.”

Twenty civilians and six regime soldiers were killed in violence in Syria on Sunday as clashes raged between deserters and regular army troops in centers of protest against the regime, human rights activists said.

Security forces shot dead 20 civilians across the country, the Local Coordination Committees, the main activist group spurring protests on the ground, reported.

Former Prime Minister Saad Hariri stressed on Saturday on the importance of confiscating the “illegal arms,” noting that the Syrian people are getting closer to their “freedom.”

“Weapons should be only with the security forces and the army,” Hariri said in English, answering a question from a Twitter user.