Still-hot volcanic material and the threat of heavy rains displacing loose deposits were posing a serious risk to the safety of emergency workers, said agency spokesman David de Leon. Around 200 people are still missing.
Rescuers scoured a lava- and ash-ravaged landscape in Guatemala for a third straight day on Wednesday in search of survivors and victims of Fuego volcano's calamitous eruption, which has killed at least 99 people.
The eruption of the 3,763-meter (12,346-foot) volcano, located 35 kilometers (21 miles) southeast of Guatemala City, was the strongest in four decades.
Rocca noted that ash had fallen across more than half of Guatemala, covering areas where agriculture is crucial.
Associated Press journalists in Guatemala have seen workers carrying five stretchers of human remains out of San Miguel Los Lotes near the Volcano of Fire.
The International Federation of Red Cross and Red Crescent Societies said they have released more than 250,000 Swiss francs ($253,446) from its global emergency fund to support frontline emergency efforts. The agency said it made a decision to suspend the search now that 72 hours had passed.
Guatemala's national disaster agency says it's suspending rescue efforts at the zone devastated by the eruption of the Volcano of Fire. The confirmed death toll has climbed to 99. That's the length of time officials had said earlier that some victims might have survived.
A U.S. Air Force C-17 has carried six Guatemalan children who were badly burned in a volcanic eruption to Texas for treatment.
Burn victims from Guatemala have arrived in Galveston to be treated at Shriners Pediatric Burn Hospital.
The children were among the victims of Sunday's eruption of the Volcano of Fire, which buried almost villages in superheated ash and debris.
It sent huge clouds of ash barreling over the surrounding area, blanketing roads, cars and people in thick gray dust as a river of molten mud carved a path down the mountain, sweeping away entire villages. Guatemala is also home to 16.3 million people with more than 9% of the population living below the global poverty line.