With winter approaching fast, the relief operation, which covers some 28,000 square kilometres of difficult terrain in Pakistan, is one of the most challenging ever undertaken, he said.
All essential infrastructure has been destroyed including roads, water systems, thousands of hospitals and schools, and government buildings, and remote areas have still not been reached because of the difficult terrain, Annan said.
He called for a major increase in funds, noting that donors have only made firm commitments for 12% - or US$37 million - of the UN appeal for $312 million. By comparison, he said, the UN flash appeal after last December's tsunami was more than 80% funded within 10 days of the disaster.
He also called on key donors and organisations including Nato and the Organisation of the Islamic Conference to mobilise helicopters, trucks, and heavy lifting equipment - and he urged donations of 450,000 more tents and temporary shelters, two million blankets and sleeping bags.
"The people and government of Pakistan are faced with an extraordinary challenge and we need to make an extraordinary effort to support them," Annan told a press conference. "What is needed is an immediate and exceptional escalation of the global relief effort to support the work of the government of Pakistan."
"What is needed is an immediate and exceptional escalation of the global relief effort to support the work of the government of Pakistan"
The latest death toll stands at 42,000 with at least 67,000 people injured, 'but because we still have not accessed hundreds of thousands of people in remote areas, we fear that the actual figures are far higher," Annan said.
"And unlike some natural disasters, in which victims die immediately, the death toll in Pakistan is not over yet," Annan warned.
"An estimated three million men, women and children are homeless," he said. "Many of them have no blankets or tents to protect them against the merciless Himalayan winter."
"That means a second, massive wave of death will happen if we do not step up our efforts now,' Annan warned.
The secretary-general said he will be attending an emergency donors' conference in Geneva next week, which the United Nations is convening, and he urged governments and other organisations to attend at the highest level.
Kofi Annan has called for an
escalation of relief efforts
"There are no excuses," he said. "If we are to show ourselves worthy of calling ourselves members of humankind, we must rise to this challenge. Our response will be no less than a measure of our humanity."
In Pakistan, high casualty estimates were reported on Wednesday in the two hardest-hit Pakistani regions.
Citing reports from local authorities and hospital officials, the government of North West Frontier Province said 37,958 people had died there and the toll was likely to rise. The prime minister in Pakistani-held Kashmir said at least 40,000 people died in the region.
In Indian-controlled Kashmir, authorities have reported 1360 deaths.