Pakistan is an experiment for US/UK/IRAN - given - thousands dead, millions homeless - facing cholera and riots

Aug. 15: U.N. Secretary-General Ban Ki-moon, right, talks with Pakistani Interior Minister Rehman Malik, left, upon his arrival at Chaklala airbase in Rawalpindi, Pakistan, to survey flood-ravaged Pakistan. (AP photo)
SUKKUR, Pakistan – SUKKUR, Pakistan -- U.N. Secretary-General Ban Ki-moon said Sunday the flooding in Pakistan was the worst disaster he had ever seen, and urged foreign donors to speed up assistance to some 20 million people affected.

Ban spoke after flying over some of the worst-hit areas.

"This has been a heart-wrenching day for me," he said alongside President Asif Ali Zardari. "I will never forget the destruction and suffering I have witnessed today. In the past I have witnessed many natural disasters around the world, but nothing like this."

The floods began more than two weeks ago and have hit about one-quarter of the country. Huge swaths of land remain under water, and hundreds more homes were flooded over the weekend.