Foreign Minister Mevlüt Çavuşoğlu on Friday called on Russia and Iran to "stop" the Assad regime bombardment of the opposition-held enclave of Eastern Ghouta after more than 400 civilians were killed in the region since Sunday.

"Russia and Iran must stop the regime," Çavuşoğlu said. He added that the offensive in the enclave as well as in the opposition-held Idlib province was "contrary" to agreements negotiated by Ankara, Moscow and Tehran during the Astana process.

A new wave of bombs struck Syria's Eastern Ghouta unabated on Friday, witnesses said, ahead of a U.N. Security Council vote to demand a 30-day ceasefire across the country.

For a sixth straight day, warplanes have pounded the densely populated agricultural pocket east of the capital, the last rebel bastion near Damascus.

The recent escalation has killed at least 426 people and injured hundreds more, the Syrian Observatory for Human Rights monitoring group says. The dead include at least 98 children.

The Britain-based Observatory said government warplanes and artillery hit Douma, Zamalka, and other towns across the enclave in the early hours on Friday.

The U.N. Security Council was considering a resolution, which Kuwait and Sweden drafted, demanding "a cessation of hostilities throughout Syria for all military operations" for 30 days to allow aid deliveries and medical evacuations.

The vote is set to take place on Friday. The resolution does not cover the Daesh, al Qaeda and the Nusra Front, which Moscow and Damascus say they have targeted in Eastern Ghouta.

Several previous ceasefire attempts in Syria have quickly unraveled throughout the multi-sided conflict, which has killed hundreds of thousands and displaced 11 million people.