UN aid trucks to move only after Syrian regime issues letters authorising the deliveries, says United Nations Special Envoy for Syria.
A nationwide ceasefire in Syria has brought a significant drop in violence and with it the hope that much-needed aid could finally be delivered to besieged areas across the country, the United Nations said on Tuesday.
Although there was some violence after sunset on Monday, by early morning the guns had fallen almost entirely silent, and UN aid trucks should be able to move very soon if the Syrian regime issued authorisation letters, United Nations Special Envoy for Syria, Staffan de Mistura said.
"Today calm appears to have prevailed across Hama, Latakia, Aleppo city and rural Aleppo and Idlib, with only some allegations of sporadic and geographically isolated incidents," de Mistura told reporters in Geneva.
"Sources on the ground, which do matter, including inside Aleppo city, said the situation has dramatically improved with no air strikes."
Damascus and central Syria were also calm but there were some reports of clashes between regime and opposition forces around Harasta and fighting in Quneitra between regime forces and the Jabhat Fateh al-Sham, a group that is excluded from the ceasefire and was formerly called al-Nusra Front.
The most delicate parts of the agreement, brokered by the United States and Russia, were to avoid the fighting snowballing and to disengage armed opposition groups that are observing the truce from those that are not. De Mistura said that would be "quite a challenge" and needed to be done within a week.
If the truce sticks, UN aid should go in very soon, and the people of Syria can look forward to "no bombs and more trucks", de Mistura said.
The Syrian Observatory for Human Rights said that it had received not a single report of combatants or civilians killed by fighting in any areas covered by the truce.
The ceasefire, brokered by the United States and Russia, is supported by countries that back Assad and his opponents, and marks the second attempt this year to halt a war that has frustrated all peace efforts since fighting began more than five years ago.
Commenting on the Syria ceasefire deal on Monday, Turkish President Recep Tayyip Erdogan said, "If it works out, the truce will be extended one more week and then will be continuous," adding that food, clothes and toys provided by both the UN and the Turkish Red Crescent would be delivered mainly to citizens in Aleppo.
Security sources, who spoke on condition of anonymity due to restrictions on talking to the media, said around 20 trucks carrying mostly food and water, crossed into Syria from the Turkish border town of Cilvegozu, some 40 km (25 miles) west of Aleppo on Tuesday. But with security concerns, it was not clear how far into Syria they would go.
The sources added that the trucks left around noon (0900GMT) Tuesday from the Cilvegozu border gate. At least 40 trucks are expected to cross the border by the end of the day.
The UN said its trucks had not yet entered Syria and that it was still awaiting confirmation that the ceasefire was holding before sending in its convoy.
"We are waiting for this cessation of hostilities to deliver the assurances and the peace before trucks can start moving from Turkey. As I speak, that has not been the case," Jens Laerke, spokesman for the UN Office for the Coordination of Humanitarian Affairs, said in Geneva.
"We need to enter an environment where we are not in mortal danger as humanitarian organisations delivering aid."
The United Nations on Friday said the Syrian regime had effectively stopped aid convoys this month and Aleppo was almost running out of fuel.
The head of the city council for opposition-held Aleppo, Brita Hagi Hassan, expressed concern that planned deliveries would be conducted according to Russian wishes and would not meet the needs of an estimated 300,000 people living there.
Hassan told Reuters the opposition-held part of the city, which has been fully encircled by pro-regime forces for more than a week, was in dire need of fuel, flour, wheat, baby milk, and medicines.
The council wanted to play a role in overseeing the deliveries, he added, rejecting any presence of regime forces on the road expected to be used to make the deliveries.
"We need 60 tonnes of flour each day," he said.
The Observatory estimates the death toll since the start of the conflict at around 430,000, in line with UN estimates. About 11 million people have been made homeless in the world's worst refugee crisis.
The ceasefire in Syria is the second attempt this year by the United States and Russia to halt the Syrian war. Russia is a major backer of Bashar al-Assad, while the United States supports some of the opposition groups fighting to topple him.