Damascus:  A suicide bombing hit Damascus on Friday, killing 25 and wounding dozens of mostly civilians, state media said, blaming "terrorists" for the second such attack on the Syrian capital in two weeks.

State television said the "powerful explosion" hit the historic Midan quarter in the heart of the capital.

The Muslim Brotherhood again implicated President Bashar al-Assad's regime in the attack, echoing a charge leveled after the twin suicide blasts last month.

"We hold the regime, its agents and its gangs, fully responsible for this crime," the Brotherhood said in a statement in Nicosia.

The attack, which took place in a heavily populated neighbourhood near a school, killed 25 people and wounded 45 others, state television said, adding that the casualties were mostly civilians but also some security personnel.

It showed gruesome footage of rescuers gathering body parts and placing them in plastic bags, in an area where damaged cars and buses were splattered with blood.

Angry residents at the scene shouted and denounced the bombing as the work of "terrorists."

The powerful December 23 bombings sparked a swirl of claims and counter-claims over who was responsible, with the authorities saying they were probably the work of Al-Qaeda and the opposition accusing the regime.

Such counter-accusations resumed on Friday, with state media labelling the blast a "terrorist bombing" as the Muslim Brotherhood called for an international and Arab probe, saying the attack benefitted the regime.

"The killings in Syria will continue and the Syrian regime will keep hiding behind Al-Qaeda and the terrorists... unless someone confronts the regime and takes it to account for its crimes," said the Brotherhood.

The attack came as activists called for an Arab League observer mission to admit its failure to stem nearly 10 months of bloodshed and hand over to the United Nations.