Tens of thousands of protesters defied regime gunfire and took to the streets on Friday, May 11 a day after twin bombings killed dozens of people in Damascus, a monitoring group said, according to AFP.

Troops shot and wounded five protesters in the capital and 20 in the Hama town of Helfaya, where two civilians also died, and they killed one demonstrator in the northern city of Aleppo, the Syrian Observatory for Human Rights said.

Aleppo-based activist Mohammed al-Halabi said the protester died from his wounds after regime forces opened fire in the Salaheddine neighbourhood.

For its part, state television said troops killed a would-be suicide bomber in the city.

"The Syrian authorities have foiled an attempted suicide attack in Al-Shaar area in Aleppo, and killed the would-be attacker," the channel added, saying the attacker's car was laden with 1,200 kilos (2,640 pounds) of explosives.

Halabi said "thousands of people are protesting in spite of gunfire. They are condemning the criminality of yesterday's bombing."

They also condemned the United Nations for failing to stop the violence in Syria, calling for "immediate international military intervention," Halabi said.

The crackdown took place a day after Thursday's bomb attacks struck the capital during the morning rush hour. They were the deadliest in 14 months of unrest, killing 55 people and wounding nearly 400, to a chorus of international condemnation.

The United Nations called on both sides in the conflict to cooperate with a month-old ceasefire as President Bashar al-Assad's regime and the opposition traded accusations over the perpetrators of the Damascus carnage.