Updated

Syria's military began withdrawing from a major artery into Aleppo on Thursday evening, shortly after the U.N. envoy for Syria blamed President Bashar Assad's government for obstructing aid access to the contested city.

With the U.S.-Russian brokered cease-fire for the war-torn country holding for its third straight day, calls intensified to have the government permit aid access to besieged opposition areas.

The U.N. says it has 40 trucks ready to distribute aid in the country, and it would prioritize delivery to the embattled, rebel-held eastern neighborhoods of Aleppo.

PRESSURE MOUNTS ON GOVERNMENT

In Geneva, the U.N.'s envoy to Syria, Staffan De Mistura, called humanitarian access the "second dividend" of the U.S.-Russia cease-fire deal, after tapering violence.

However, de Mistura said the Syrian government had not provided the necessary "facilitation letters," or permits, to allow for convoys to reach opposition areas, disappointing even Russia, the Syrian president key backer.

Russia's military announced on Thursday evening that the Syrian military was beginning to withdraw from a contested route to Aleppo, suggesting a breakthrough to the deadlock could be coming.

CLASHES FOR IS-HELD DEIR EL-ZOUR

In the eastern province of Deir el-Zour, clashes and shelling over the past 24 hours between government forces and the Islamic State group in the provincial capital, also called Deir el-Zour, have killed at least three people, including a child, according to activists and state media.

Elsewhere in the same province, an airstrike Thursday on the IS-held town of Mayadeen killed at least four people and wounded dozens, said opposition activists and Deir el-Zour 24, an activist collective. The Syrian Observatory for Human Rights monitoring group said the airstrike killed seven people. It wasn't known who carried out the airstrike.

The cease-fire does not cover territory held by the Islamic State group.