Speaker after speaker took the floor at a plenary meeting of the United Nations General Assembly on Thursday to call for global solidarity to help flood-hit Pakistan in the wake of the Asian country's worst disaster in living memory and for generous support for vital relief operations.

"Make no mistake: this is a global disaster, a global challenge. It is one of the greatest tests of global solidarity in our times, " UN Secretary-General Ban Ki-moon told the 192-member body, which is expected to adopt a resolution at the end of the two-day special meeting to call for international assistance in support of the Pakistani government's efforts to address the crisis.

The secretary-general, who visited the flood-stricken country on Sunday, said Pakistan is facing a "slow-motion tsunami," with needs expected to grow, even as 15 to 20 million people currently need shelter, food and emergency care.

"That is more than the entire population hit by the Indian Ocean tsunami, the Kashmir earthquake, Cyclone Nargis and the earthquake in Haiti, combined," he stated, adding that at least 160,000 square kilometers of land is under water -- an area larger than more than half the countries of the world.

Meanwhile, Ban thanked the international community for the generosity it has shown so far, especially in response to the 460 million U.S. dollars requested by the UN and its partners through the Pakistan Initial Floods Emergency Response Plan that was launched last week, which is now 47 percent funded.

Underscoring that the needs are great, and the disaster is far from over, Ban asked nations to respond urgently to the emergency response plan and help humanitarian agencies deliver the food, water, shelter and health care that millions in Pakistan so desperately need.

More than 45 speakers, including Pakistani Foreign Minister Makhdoom Shah Mehmood Qureshi, U.S. Secretary of State Hillary Clinton and other high-level officials from a number of countries, were inscribed to speak at the meeting, which is taking place on World Humanitarian Day, dedicated to the memory of all those aid workers who have lost their lives while bringing assistance to others, and to increase awareness of relief activities worldwide.

"Today's meeting is demonstrative of the international community's commitment to act, an opportunity to step forward and show to the people and the government of Pakistan that we are ready and willing to assist them in every possible way," said Ali Treki, the president of the 64th session of the UN General Assembly.

The president called on member states to donate generously in the face of the "unprecedented humanitarian disaster" unfolding in Pakistan. "This is an extraordinary emergency situation," he said. "It requires an extraordinary response."

The floods, which began late last month in the wake of particularly heavy monsoon rains and which have destroyed homes, farmland and major infrastructure in large parts of the country, have claimed more than 1,200 lives.

Earlier on Thursday, a top UN relief official in Pakistan warned that if humanitarian assistance for clean water, food, shelter and health care is not provided soon enough, there could be a second wave of deaths caused by waterborne diseases.

"The death toll in this disaster has miraculously been far lower than in some other major recent natural disasters and we wish to keep it that way," UN Humanitarian Coordinator Martin Mogwanja told reporters in New York, speaking from Pakistan.

The World Health Organization (WHO) also urged greater donor support for health projects in Pakistan, where more than 200 health facilities have been damaged or destroyed, adding that reports from the field already indicate a significant rise in the number of cases of acute watery diarrhea, skin infections and malaria.

"It is crucial that all humanitarian health providers, local and national, coordinate their relief efforts closely to save lives, reduce suffering and deliver the most effective response," said WHO's Representative in Pakistan, Guido Sabatinelli.

Mogwanja noted that a food crisis is also possible given that thousands of hectares of crops which were due to be harvested in the next four weeks in most parts of the country have now been destroyed. It is therefore vital for food aid to reach those affected as soon as possible.

In the longer-term, he added, it will be necessary to assist in rebuilding livelihoods as well as public infrastructure such as roads, bridges, telecommunications, power lines and irrigation canals.

"The people of Pakistan are depending on the people of the world," he said.

For his part, the Pakistani foreign minister thanked the international community for the generosity it has shown so far and urged greater efforts to assist the Government and people of the South Asian nation.

During a meeting with the secretary-general ahead of the General Assembly session, Qureshi welcomed the leadership and commitment of the UN in the response to the disaster. The minister and Ban also discussed further steps and meetings over the coming months to bolster the relief and recovery efforts.