Trucks carrying aid entered four besieged towns in Syria, in what the United Nations described as a test for the country's warring sides ahead of a hoped-for ceasefire.
The Red Crescent said trucks laden with supplies entered Moadimayet al-Sham, near Damascus, the first delivery of aid since world powers agreed on an ambitious plan to cease hostilities by Friday and dramatically ramp up humanitarian access.
The agency's Muhannad al-Asadi told AFP that 35 trucks entered the town, "carrying 8,800 sacks of flour, 4,400 food parcels, high-energy foods and medical equipment".
An AFP journalist said three trucks also entered Madaya, a town besieged by Syrian forces in Damascus province.
And the UN's humanitarian coordinator for Syria, Yacoub El Hillo, said aid trucks had reached the Shiite towns of Fuaa and Kafraya, in northwestern Idlib province, which are surrounded by rebels.
"Dozens of trucks will follow" for Madaya, Fuaa and Kafraya, he said. "We are about the finish the process."
He said that aid dispatched Wednesday to towns, including Zabadani, under government-imposed siege in Damascus province, was enough for 93,000 people.
Almost half a million people in Syria are in areas under siege, according to the UN.
Prospects for the ceasefire -- announced by top diplomats in Munich last week -- have been fading as violence continues to shake Syria, including air strikes on hospitals and repeated Turkish shelling of Kurdish militia.
- 'Duty' to allow aid -
UN envoy Staffan de Mistura said aid deliveries would provide a "test" for Syria's warring sides ahead of Friday's planned truce.
"It is the duty of the government of Syria to want to reach every Syrian person, wherever they are, and allow the UN to bring humanitarian aid," he said in Damascus.
A senior aide to President Bashar al-Assad accused the envoy of deviating from his role as a mediator.
"His mission now is to establish a list of terrorist groups, and a list of opposition groups who should dialogue with the Syrian government," Buthaina Shaaban told AFP.
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"Instead of that he was working on humanitarian aid, which is not really his mission because he is a facilitator."
Diplomats have been pressing the ceasefire deal as a step forward in efforts to end Syria's nearly five-year conflict, which has left more than 260,000 people dead, devastated the country and forced millions from their homes.
A major international push to resolve the conflict, including Western and Arab nations that have largely backed Syria's opposition and Assad's key supporters Russia and Iran, was launched last year.
But peace talks between the regime and opposition in Geneva quickly collapsed this month and a major regime offensive, backed by Russian air strikes, has continued in northern Aleppo province.
A US military spokesman said on Wednesday that Russian and Syrian regime raids may be intensifying.
Air strikes on five medical facilities and two schools in northern Syria earlier this week killed at least 50 people, the UN said. One hit a hospital supported by charity Doctors Without Borders (MSF), prompting widespread condemnation.
- Ankara bomb kills 28 -
Further complicating peace efforts, Turkey has been shelling a Kurdish-led militia in northern Syria, which it says is allied with the outlawed Kurdistan Workers' Party (PKK) that has waged an insurgency on its soil for decades.
A car bomb Wednesday in Ankara killed at least 28 people and wounded 61 more, but no group claimed responsibility for the blast. Turkey has blamed the PKK and the Islamic State group for previous bomb attacks.
President Recep Tayyip Erdogan vowed that Turkey would never accept the creation of a Kurdish stronghold in northern Syria, saying there was "no question" of Ankara ending its shelling.
Hundreds of rebels Wednesday crossed the Turkish border heading for the flashpoint Syrian town of Azaz, where opposition groups have suffered setbacks against Kurdish forces, said monitoring group the Syrian Observatory for Human Rights.
"At least 500 rebels have crossed the Bab al-Salama border crossing on their way to Azaz, from which they want to help the insurgents in the face of gains made by Kurdish forces in the north of the province," head Rami Abdel Rahman told AFP.
Israel also targeted regime forces with three air strikes south of Damascus on Wednesday evening, the Observatory said.
Turkey has called for foreign ground forces to deploy in Syria, part of a longstanding push by the NATO member for a more robust response to the conflict in its neighbour.