JEDDAH: The secretary-general of the Organization of Islamic Cooperation (OIC) on Sunday called on the international community to intervene and stop the attacks on the Syrian city of Aleppo.

Iyad Ameen Madani said the “continuous shelling of civilians in the besieged city and the destruction of humanitarian convoys are war crimes for which the Syrian regime must be held accountable.”

Madani said the “parties supporting the regime must bear the responsibility for the continuation of these violations,” an apparent dig at Russia and Iran which are actively supporting the government of dictator Bashar Assad.

Last week, amid a truce a UN humanitarian convoy was delivering relief goods to stranded civilians in Aleppo when it was hit in a strike by warplanes believed to be of Syria and Russia. A Red Crescent staff and 11 civilians were killed in the attack.

Madani said the parties that pledged to stop the hostilities and enforce a humanitarian truce must “intervene immediately to stop the

killing and massacres.”

He also urged the United Nations “to act in accordance with its responsibility under the Charter to stop these dangerous

violations of the international humanitarian law being committed in Aleppo.”

Madani noted that when he met with UN Secretary-General Ban Ki Moon at the UN Headquarters on the sidelines of the UN General Assembly last week, the topic was about the deteriorating situation in Aleppo.

As of Saturday, rebel-held parts of Aleppo had come under a blistering wave of airstrikes that residents said was without precedent in the 5 1/2-year conflict which has killed over 300,000 people and driven half the country’s population from their homes. The airstrikes killed dozens, toppled buildings and sent wounded people flooding into poorly equipped clinics.

Aid was never delivered to Aleppo, and on Saturday government forces captured an area on the edge of the city, tightening their siege around the rebel-held east.

Global reaction was swift and condemned the new Syrian offensive in harsh terms.

UN Secretary-General Ban “is appalled by the chilling military escalation” in Aleppo and underlines that the use of indiscriminate weapons including incendiary devices and bunker buster bombs in densely populated areas “may amount to war crimes,” his spokesman said, adding that Ban considers this “a dark day for the global commitment to protect civilians.”

US Secretary of State John Kerry, called the bombing of Aleppo “beyond the pale,” accusing the Syrian government of “laying siege in medieval terms to an entire community.” Speaking at Tufts University in Boston, he demanded that Russia help bring peace to Syria instead of “an unacceptable precedent ... for the entire world.”

But Syrian Foreign Minister Walid Al-Moallem on Sunday said Syria is more determined than ever to eliminate “terrorism” from the country.

The Syrian government refers to all those fighting to overthrow President Bashar Assad as “terrorists,” including Western-backed opposition groups.

Al-Moallem accused the “moderate armed opposition” of committing crimes and massacres against Syrians “that are no less barbaric” than those of the Daesh extremist group and Al-Qaeda.

The Syrian government in turn has been accused by the US and other Western nations of the indiscriminate killing of civilians, dropping bombs filled with chlorine gas as a chemical weapon, and torturing and killing opponents.

The Syrian official addressed the UN General Assembly’s annual ministerial meeting after frantic but unsuccessful efforts by the US and Russian foreign ministers to revive a cease-fire that came into effect on Sept. 12 but collapsed after a week following attacks by both sides.

(Additional input by the Associated Press)