Trucks from the Syrian Arab Red Crescent carrying medical aids head to Douma city in the countryside of Damascus, Syria, 13 February 2016. (Youssef Badawi/EPA)

With peace talks between Syria's warring parties set to continue in Geneva, the country's parallel ceasefire has not solved the immediate plight of hundreds of thousands of residents in areas predominantly besieged by regime forces, the UN and aid groups warned this week.

Speaking on Thursday in Geneva, Syria humanitarian task force coordinator Jan Egeland said he was "disappointed and disheartened" at delays and outright denial of access for humanitarian convoys in the past week.

"We had five convoys ready to go and for the last four days all of the five convoys could not go," Egeland told reporters. Four of the convoys, he said, required approval by the regime. As a result, some 287,000 people in areas the UN considers hard-to-reach or besieged received no aid.

"Most of these issues are related to the government," he said.

Last week, the UN's Humanitarian Coordinator Stephen O'Brien told the Security Council that several regime besieged areas, including Daraya and Duma, were inaccessible despite being "mere minutes' drive from UN warehouses in Damascus."

After the Security Council meeting, US ambassador Samantha Power said "not one crumb of food has reached Daraya since 2012."

In Geneva, Egeland called attention to the deaths of three boys in the Hezbollah-besieged town of Madaya, also located on the outskirts of Damascus. Under the so-called "Four Towns" agreement reached last September with UN assistance, aid convoys to Madaya and nearby Zabadani are allowed through only if equivalent access is given to two rebel-besieged towns, Foa and Kefraya, in northern Idlib province.

Last week, VICE News investigated the circumstances of the boys' deaths. The three children were all gravely wounded when a mine they found, likely laid by Hezbollah militants, exploded; at least one of them, Egeland confirmed, probably would have lived if transport had been allowed to travel to a hospital in Damascus. But Hezbollah insisted that if no one required medical evacuation from the two towns in Idlib, no one would be allowed out of Madaya.

While Egeland has repeatedly criticized the government of Bashar al-Assad for blocking humanitarian deliveries, the UN's special envoy for Syria, Staffan de Mistura, who helped broker the four towns agreement and oversees talks in Geneva, has been more hesitant. Asked about the incident in Madaya last week, his office referred reporters to earlier comments made by Egeland.

On Friday, UN spokesperson Stephane Dujarric defended the four towns arrangement, telling reporters in New York, "you have to start somewhere, you have to start small."

According to the medical charity Doctors Without Borders (MSF), five people died in Madaya over the last week, three of whom — one of the boys, an older person with vascular disease and a man who died from malnutrition — "could probably have been stabilized if urgently-called-for medical evacuations had been permitted." The group said that more than one hundred people in Madaya were suffering from malnutrition.

The best trained medical professional in Madaya is a dentist. In adjoining Zabadani, where rebels are concentrated, there was one medical doctor — until recently. He was killed by a sniper last week.

In New York, Dujarric criticized the pattern of denial of access and evacuations, implying that the four towns agreement was being abused by the regime and its allies.

"We are now in a bizarre situation where there has to be a tit-for-tat or quid pro quo for evacuations where people's medical needs are subjugated to political realities," he told reporters at a press conference.

The day prior, Egeland said that as many as 500 people could be evacuated from the four towns in the "near future." In January, O'Brien reported that 400 residents of Madaya alone were in need of "immediate" medical evacuation. According to the World Health Organization, only 18 sick or injured residents had been allowed to leave as of last week.

Egeland also pointed out that 15 of the 18 areas considered besieged by the UN in Syria are surrounded by regime or allied forces. Mathematically, there simply aren't enough rebel besieged areas to replicate the four towns arrangement across the country.

Even in convoys that are allowed through, the UN and aid organizations say shipments of vital medical equipment, including materials to treat victims of airstrikes, are inexplicably being blocked. According to the UN, some 80,00 medical treatments have been removed or excluded from convoys in just the first months of 2016, mostly by the regime.

Elsewhere, MSF reported that airstrikes hit two hospitals it supports in the besieged suburbs of Eastern Ghouta, "leading to at least 38 killed and 87 wounded."