Rebels control swathes of Yarmuk, but for months government forces have imposed a suffocating siege on the camp, where some 20,000 Palestinians live despite terrible shortages.
Palestinian labour minister Ahmad Majdalani, who was visiting Damascus to negotiate aid access to the camp, said its Palestinian residents must not be used as "hostages" in the conflict.
An aid convoy heading to Yarmuk was targeted yesterday "some 100 metres (yards) away from the agreed meeting point," on the edges of the camp, Majdalani said at a press conference in Damascus.
Majdalani added "all these groups are known for their terrorist links and methodology."
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The minister also said Palestinians "everywhere know... that those who have taken the camp hostage are these groups, not the Syrian authorities."
Some 45 people have died in recent months because of food and medical shortages in Yarmuk, the Syrian Observatory for Human Rights monitoring group has said, with the most recent death today.
Yesterday's aid convoy was the sixth to have failed to enter the camp.