The UN Office for the Coordination of Humanitarian Affairs (OCHA) says several issues of a "logistical nature" have delayed aid deliveries to besieged areas of Syria.
Jens Laerke, a spokesman for the UN body, said on Wednesday that “a much simpler procedure” is needed for the assistance to proceed.
The remarks came after a ceasefire agreement in Syria brokered by Russia and the United States entered into force on February 27. The Syrian government accepted the terms of the truce on condition that military efforts against Daesh and the al-Nusra Front Takfiri militants, who are excluded from the ceasefire, continue.
Following the implementation of the truce, the UN said on Monday that it is seeking to deliver aid to about 154,000 people over the next five days in the Arab country.
The Damascus suburb of Moadamiyeh received some assistance, but the rest of the aid has been held up.
"It’s a mixture of things" including "facilitation letters" that are still pending with the Syrian government, Laerke added.
Syria has been gripped by foreign-backed militancy since March 2011. According to a February report by the Syrian Center for Policy Research, the conflict has claimed the lives of over 470,000 people, injured 1.9 million others, and displaced nearly half of the country’s pre-war population of about 23 million within or beyond its borders.
Damascus accuses Saudi Arabia, Turkey and Qatar of funding and arming anti-Syria terrorist groups, including the Daesh Takfiri group.