The first civilian deaths since a ceasefire took effect in Syria were reported Thursday, while opposing sides in the conflict continued to hold back aid deliveries to hundreds of thousands of people.
The Syrian Observatory for Human Rights reported the casualties, saying they were two children. One was killed in al Hader in the northern countryside of Queintra, when opposition rebels fired shells on the area. The other was killed by a sniper in the regime-held area of al Masharqa in western Aleppo.
Earlier, the United Nations Syria envoy Staffan de Mistura put most of the blame for the delay in aid delivery on the government of President Bashar al-Assad, which has not yet provided any so-called facilitation letters required by aid trucks to access civilians in need across the country.
"This is something that is required to take place immediately," he told reporters in Geneva.
The truce, brokered by the United States and Russia, has been largely holding since Monday, but 40 aid trucks with supplies are being held up on the border with Turkey, De Mistura said.
There appeared to be some positive movement, however, when Syrian government forces started to withdraw from the Castello Road, a key route to the besieged rebel-held eastern part of Aleppo. Russian monitors are in the area.
"Finally, the Syrian government is fully ready for withdrawing troops from Castello Road, simultaneously with the opposition, to ensure safe passage of UN humanitarian convoys," Russian Defense Ministry spokesman General Igor Konashenkov was quoted as saying by state news agency TASS.
"We do not know if this is a real withdrawal or repositioning," said the Observatory, but confirmed the Russian information and noted this could pave the way for aid to reach people inside.
The rebels themselves have voiced strong opposition to letting in aid via the Castello route, fearing this would end up favouring the government and cementing its control over the road, allowing al-Assad's forces to reintroduce a siege in the future.
Up to 275,000 people in east Aleppo have been cut off from assistance since early July. Overall, 600,000 Syrians are living in besieged or hard-to-reach areas, according to the UN.
De Mistura noted that even the Russians were expressing frustrations with the Syrian government over its blockade.
Contrary to the rest of Syria, aid convoys will not need government pre-approval for accessing the rebel-held eastern part of Aleppo. De Mistura said he expected Damascus to honour this rule, and to let trucks pass without removing medical supplies this time.
He also noted that rebel-controlled local authorities have yet to guarantee unhindered deliveries of aid. The Russians accused rebels of violating the ceasefire and Konashenkov said that "only the Syrian military is observing the truce."
The Observatory, meanwhile, raised the death toll from airstrikes by unidentified planes on an Islamic State-controlled area in Deir al-Zour in eastern Syria to 23, among them nine children.
Islamic State affiliated Amaq news agency also reported the strike, blaming Russia.
Both Russia and the United States consider Islamic State and al-Qaeda fair targets during the truce, and neither extremist organization signed on to the cessation of hostilities.
Konashenkov blamed the US for "its failure to honour its part of the commitments, especially on disengaging the moderate opposition." The US, which supports some moderate rebel factions, is working to solve this issue.
Rebel groups fight alongside al-Qaeda-linked militants against al-Assad's forces, as the extremists are among the most potent fighting forces in the country. The US has said the rebels will soon need to separate themselves from the extremists.
In depth coverage
A ceasefire in Syria was holding Thursday, despite a limited number of reported breaches, but humanitarian aid supplies have not yet entered the country and are being held up on the border with Turkey.