Updated

EU foreign policy chief Federica Mogherini is calling on Russia, Iran and Turkey to force a halt to fighting in Syria, as international donors gather in Brussels to drum up aid for the conflict-ravaged country.

Mogherini told reporters Wednesday that the three have a "special responsibility" to ensure the conditions for a cease-fire and to pressure Syrian President Bashar Assad to return to the negotiating table.

"We are seeing an escalation in military activities which is exactly the contrary" to what they promised to work toward, she said.

Around 80 countries, organizations and partners backing Syria are taking part in the donor conference in Brussels.

Organizers hope the meeting will give impetus to stalled peace moves under U.N. auspices, on top of gathering several billion dollars in humanitarian aid.