Qatar warned Saturday that Syrian regime air strikes that killed more than 30 people including children in a rebel-held town near Damascus could "torpedo" a fragile ceasefire in the country.

Saudi Arabia also accused the regime of violating the ceasefire and said President Bashar al-Assad was "insisting on foiling all ongoing international efforts to politically resolve the Syrian crisis".

The Syrian Observatory for Human Rights, a monitoring group, reported that 33 people, including 12 children, died in air strikes Thursday on Deir al-Assafir, a town in the opposition stronghold of Eastern Ghouta.

"Qatar expresses its strong condemnation and concern over the massacre by Syrian regime forces targeting civilians in Deir al-Assafir... in a violation of the cessation of hostilities agreement and related UN Security Council resolutions," the foreign ministry in Doha said in a statement.

Eastern Ghouta is among the areas in Syria where a fragile ceasefire brokered by the United States and Russia has been in place since February 27.

"This criminal shelling... reflects the regime's policy in killing civilians... and threatens to torpedo" the ceasefire and "international efforts to reach a political solution" to end the country's five-year war, said the statement, carried by the official Qatar News Agency.

In a statement on Saudi state news agency SPA, a foreign ministry source said the kingdom condemned "in the strongest terms" the "ugly massacre by forces of Bashar al-Assad, the criminal",

The attacks were a "continuation of his (Assad's) crimes against the Syrian people and his violation of the cessation of hostilities".

Qatar and Saudi Arabia support Syrian rebels fighting Assad's Russian- and Iranian-backed regime.

The United States said Thursday it was "appalled" by the Syrian government air strikes and France accused Assad's regime of violating the ceasefire and trying to undermine efforts by the international community to resolve the conflict.

Qatar urged the Security Council to "assume its responsibilities to end these crimes, protect the Syrian people, and prevent (attempts to) undermine chances of reaching a political settlement to the Syrian crisis."

UN-led talks on a peace deal are deadlocked over the fate of Assad, whom the opposition insists must leave power before a transitional government is agreed.