A general view for the besieged Syrian town of Madaya. Convoys carrying humanitarian supplies, the second in a week, were on their way to the town and two others. (Youssef Badawi/European Pressphoto Agency)

Opposition figures in Syria accused the United Nations on Thursday of acquiescing to the Syrian government’s practice of denying food and medicine to tens of thousands of people in besieged areas.

In an open letter addressed to Stephen O’Brien, the U.N. undersecretary for humanitarian affairs, 112 Syrian civil society activists accused the world body of “complicity” in government-
imposed blockades that violate the laws of war.

The criticism highlights the complexity of delivering humanitarian aid in such a messy war, which involves sieges imposed by forces loyal to Syrian President Bashar al-Assad and by his opposition in multiple areas.

The letter comes two days after desperately needed food convoys enabled by a U.N.-backed agreement reached Madaya, an ­opposition-held town blockaded by pro-Assad forces. The letter was released ahead of U.N.-supported peace talks between the government and opposition that are scheduled to start Jan. 25.

In an email, Jens Laerke, deputy spokesman for the U.N. Office for the Coordination of Humanitarian Affairs, said U.N. officials have repeatedly voiced concern for people living in besieged areas. He said that despite repeated requests by U.N. agencies to deliver “lifesaving” aid, parties on both sides of the conflict have often “failed to respond positively.”

The United Nations said this month that just 10 percent of requests made by its agencies to dispatch aid convoys to besieged or hard-to-reach areas in Syria received approval last year.

Another U.N. official involved in the humanitarian effort in Syria said it would be dangerous in such a violent conflict zone to attempt to deliver aid without government consent. Otherwise, aid convoys would face an elevated risk of attack, said the official, who spoke on the condition of anonymity because of a lack of authorization.

In the letter, the activists, who include doctors, teachers and emergency responders, describe U.N. agencies as being too willing to seek permission from the Assad government to deliver relief. The activists note that international law and a 2014 U.N. Security Council resolution oblige all warring parties not to disrupt the delivery of humanitarian aid.

“By allowing the [Assad] regime to veto aid to civilians in areas outside its control, you have allowed the U.N. to become a political tool of the war,” the letter said, adding that international humanitarian aid readily flows to ­government-held territory.

The letter — compiled and distributed with the help of the Syria Campaign, an activist group critical of Assad — said that U.N. staff members in Damascus, the Syrian capital, “are either too close to the regime or too scared of having their visas revoked by the same powers that are besieging us.”

An estimated 400,000 people in Syria are living in areas under siege by government and opposition forces, a long-running issue in the nearly five-year-old crisis that has led to more than 250,000 deaths.

This undated photo posted by the Local Revolutionary Council in Madaya, which has been verified and is consistent with other Associated Press reporting, shows a starving boy in Madaya, Syria. (AP)

The Islamic State militant group is surrounding about 200,000 people in the Deir al-Zour area of eastern Syria. And just a few miles from Assad’s seat of power in Damascus, his forces have maintained a years-long blockade on the rebel-held suburbs of Eastern Ghouta, where tens of thousands of people live. The area has also been regularly carpet-bombed.

On Wednesday, a number of influential rebel groups refused to participate in this month’s peace talks in Geneva unless the Assad government allows humanitarian aid into areas besieged by its ­forces.

Attention recently has centered on the siege of Madaya, which is near the border with Lebanon and had been cut off from food and medicine by government forces since the summer.

On Monday, a U.N.-backed agreement involving the Assad government allowed for a convoy carrying food and medicine to reach the more than 20,000 people in the town. Aid officials expressed alarm at the extent of starvation suffered by residents of Madaya.

Majed Abo Ali, a spokesman for the Unified Medical Office of Eastern Ghouta, a Syrian nongovernmental organization, said that Thursday’s letter to the United Nations signals mounting frustration in areas cut off by government forces.

In particular, he noted, recent U.N. efforts to help broker cease-fire deals in government-besieged areas, such as the city of Homs, have fostered suspicion among residents. Those cease-fires are commonly known in rebel areas as “surrender or starve” agreements: If rebels do not surrender to government forces or flee the area, they and their families generally must resist while being cut off from food.

“The U.N. has tools to pressure the government, but it’s not using them, and people are starving as a result,” said Abo Ali, whose organization is a signatory to the letter.

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