Jeremy Moodey, from Embrace the Middle East, was speaking after the UN suspended all convoys in Syria following deadly air strikes on aid trucks the previous night.
The International Committee of the Red Cross (ICRC) said around 20 civilians were killed in the air strikes that hit an aid convoy in northern Syria.
The statement said the civilians were killed as they were unloading trucks carrying vital humanitarian supplies and that much of the aid was destroyed, depriving thousands of much-needed food and medical assistance.
ICRC president Peter Maurer says the attack was a "flagrant violation of international humanitarian law" and "totally unacceptable".
The Syrian military, just hours earlier, had declared that a week-long ceasefire had failed because rebel groups kept breaking it.
Russia and Syria, who operate in the airspace where the convoy was, have denied bombing it.
Speaking on Premier's News Hour, Jeremy Moodey said: "It will have a terrible impact. People are really suffering. There was a desperate need to get aid into these communities. That was the reason for the ceasefire that was agreed, so to see it collapse is tragic.
"People will starve and die."
Martijn Hekman, the Deputy Director of Christian charity World Vision's Syria Response, said: "This deadly attack is a horrific turning point in the conflict, and utterly devastating for thousands of children and their families who were waiting for these supplies to arrive.
"We can only hope this attack will serve as a wake-up call to leaders to salvage what's left of last week's ceasefire deal and redouble their efforts."
Listen to Premier's Antony Bushfield speaking to Jeremy Moodey:
