Mr Ban said the Philippine government needs more help to mitigate the impact Typhoon Haiyan, which slammed into eastern and central provinces on Nov 8, killing more than 6,000 people and displacing more than 4 million.
"I'm appealing to the international community to speed up and scale up their support," he said in Manila one day after he visited Tacloban City, the capital of the worst-hit province of Leyte.
"They need this support immediately because there are still shortages of food, water and sanitation, and they need shelter," he said. "Having visited Tacloban, my impression is that the situation is still very dire."
Mr Ban said that he was impressed by the survivors' resilience and their motivation to move on, but added they must have sustained assistance to be able to rebuild stronger communities.
"People are working hard to recover," he said. "We must not allow this to be another forgotten crisis."
The UN has already made an international appeal for emergency assistance worth US$791 million (25.3 billion baht). But only 33% of that amount has been funded so far. The Philippine government has launched a four-year, $8.17 billion recovery plan for the affected areas.
According to the national disaster relief agency, 6,109 people were killed in the storm and 1,779 are still missing. More than 27,000 people were also injured.
The typhoon, one of the world's strongest on record, caused damage to agriculture and infrastructure worth an estimated 36 billion pesos (26 billion baht), the agency said.