Updated

Top U.N. officials say they are working urgently with other key players to determine how best to implement a new Security Council resolution calling for cross-border delivery of humanitarian aid to rebel-held areas in Syria without government approval.

Humanitarian chief Valerie Amos and the heads of the World Food Program and the U.N. children's agency said in a joint statement Wednesday that the resolution adopted Saturday "represents a breakthrough in our efforts to get aid to Syrians in need" and could help up to 2.9 million people.

WFP teams on the ground are proceeding immediately to put in place a system to monitor aid shipments, and UNICEF has already positioned supplies for the first cross-border convoys, including blankets, water purification materials, hygiene kits and syringes, the statement says.