Aid agencies face an increasing struggle to reach communities trapped in Syria's worsening civil war, UN humanitarian chief Valerie Amos said Thursday.
Amos highlighted the case of the Yarmuk Palestinian refugee camp in Damascus where the UN says at least 15 people have died from malnutrition in recent weeks.
The UN has had no access to the camp, which houses some 20,000 people, since September.
The United Nations has pressed the Syrian government and opposition for greater access since the UN Security Council demanded more cooperation from President Bashar al-Assad's government in October.
Yarmuk is "one of the areas we are continually trying to seek access to, we haven't had any success to date with respect to Yarmuk. We will keep trying," Amos told reporters.
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The UN under secretary general for humanitarian affairs said there had been an improvement in Syria's allocation of visas for UN workers and opening new humanitarian centers.
"We saw initially a greater number of convoys that were able to move. That number decreased in December because of ongoing security concerns."
The UN was able to organize nine humanitarian convoys in November, against a monthly average of three.
"On the major issues, around protection of civilians, around demilitarization of schools and hospitals -- for example, getting into those besieged communities -- we have not seen any progress in those areas," Amos said.
Amos said she would brief the Security Council in coming weeks, and diplomats said more international focus would be put on humanitarian access in Syria.
The $6.9 billion appeal launched by the UN for Syria this year is the biggest in the global body's history.