Syrian opposition figures denounced the explosion that rattled the heart of the Syrian capital of Damascus Friday, calling for embarking on a national dialogue to help bring the months-long crisis in the Middle East country to a close.

A suicide bombing ripped through al-Midan neighborhood in Damascus Friday, killing at least 25 people and leaving dozens of others wounded.

"The blast that has occurred today is suspicious and it's a result of the ongoing violence practiced by the authorities, who haven't abided by the Arab League peace plan," said Hasan Abdul- Azim, head of the opposition National Coordination Body.

"We can't accuse any party without solid evidence," he said, adding that "we condemn any criminal act regardless of who stands behind it and we stress that the Syrian revolution should remain peaceful because it's the only guarantee for it to triumph."

George Gabbour, a political analyst and former parliamentarian, told Xinhua that "I don't have any reason to question the official statement by the government on today's blast."

"Some opposition parties accused the Syrian leadership of being behind the blasts in Damascus, but most people don't believe so," Jabbour said, adding that "the opposition should present an evidence to substantiate its claims otherwise its accusations are just talks."

Right after the bombing, head of the so-called Syrian Free Army, a Turkish-based anti-government militia group allegedly comprised of army defectors, condemned the bombing and blamed the regime of President Bashar Assad for the blast.

In a phone interview with the Qatari al-Jazeera TV, Riad Asaad, a breakaway air force Col, said that he has about 35,000 defectors across Syria.

He confessed that his groups had carried out attacks over that past days against the Syrian army, and pledged that "we will surprise the Assad-regime with more qualitative operations."

The bombings represent an escalation of violence in Syria at a time when the Arab League observers are touring the country to monitor the nearly 10-month-old unrest on ground.

"I believe that the climate is suitable now for all Syrians to embark on a national inclusive dialogue with the presence of Arab observers," Jabbar said, adding that "the people should decide the style of rule that they want."

The head of the Arab League observers' mission in Syria immediately visited the site of the blast Friday, according to witnesses and official sources.

Arab League observers started on Dec. 27 a monthlong mission to verify Syria's commitment to an Arab plan to end the nearly 10- month-old unrest, which the government blamed on foreign conspiracy and armed groups.

Meanwhile, the Syrian Interior Ministry said Friday in a statement that the explosion was carried out by "armed terrorist groups that target the Syrian people's security and lives."

A suicide bomber blew himself up at a traffic light, killing at least 25 people and wounding 63 civilians and policemen, it said, adding that the explosion caused severe damage to parked cars and nearby buildings.

It said forensic experts gathered parts of the torn bodies and the explosive material "to identify the terrorists."

The initial investigations revealed that the explosives weigh more than 10 kilograms, said the statement, adding that specialized authorities have started investigations to disclose the motives of the "terrorist acts." The ministry vowed to beat with an "iron fist" whoever tries to mess with the country's security, urging residents to cooperate with Syrian authorities by reporting any "suspicious" case and submit information concerning the terrorists' activities and moves.

Also, the National Leadership of al-Baath Arab Socialist Party said that the timing of the terrorist attack reflects the criminal mentality of perpetrators and their antagonism towards moral heritage and national values.

In a statement issued on Friday, the leadership said the attack is "part of the conspiracy against Syria."

It said that the continuation of the terrorist acts targeting innocent civilians makes it imperative for the human, Arab and international organizations to condemn these acts and the ones behind them.

Last month, two suicide car bombers blew up themselves in front of two security headquarters in Damascus, killing at least 40 people and injuring 166 others. The Syrian authorities said the then-explosion bore the hallmarks of al-Qaida.

The Syrian government said a total of 2,000 army and security personnel were killed during the months-long unrest, while the United Nations put the death toll in the country at more than 5, 000.