ISLAMABAD, Pakistan, Aug. 16 (UPI) -- U.N. Secretary-General Ban Ki-moon, after visiting the "heart-wrenching" devastation of flood-stricken Pakistan Sunday, stepped up his appeal for international aid.
"This has been a heart-wrenching day, and I will never forget the destruction and suffering that I have witnessed," Ban told reporters Sunday after visiting some of the flood-hit areas.
The number of people affected by the disaster has reached nearly 20 million, Ban said.
"I have witnessed various disasters across the world, but nothing like this, as the scale of this disaster is so large that one out of every 10 Pakistanis has been affected," he said.
"I am here also to urge the world community to speed up assistance to Pakistan."
Ban said only 25 percent of the estimated $459 million in aid needed for initial relief efforts has arrived so far.
Ban announced an additional $10 million for the relief efforts, to come from the U.N. Central Emergency Response Fund, bringing the total U.N. assistance to $27 million.
Ban said he would report to the General Assembly Thursday to mobilize all necessary assistance.
The floods, which began to hit Pakistan at the end of July during the monsoon, have now covered at least one-fifth of the country's surface, an area of 62,000 square miles. Heavy rains are expected to continue for a few more weeks.
At least 1,600 people have been killed in the disaster, with millions remaining homeless.
The United Nations has also increased its estimate for the country's agricultural losses, saying about 8 million acres of standing crops -- or about 17 percent of Pakistan's cultivable area -- and 925,000 head of livestock have been destroyed.
Damage to irrigation systems and the loss of grain stocks, seed and farming equipment have made farmers "extremely vulnerable," the United Nations said, emphasizing that their situation would worsen if they are not able to sow the staple wheat crop in September and October.
"If this season is missed … the impact on agricultural livelihoods and household food security will be catastrophic, resulting in long-term dependence on food assistance," the United Nations said in a report Saturday.
One case of cholera was confirmed in the northwest part of the country, the United Nations said, and health workers are preparing for an onslaught of up to 140,000 cases of the disease.
"With the potential spread of diarrhea and other waterborne diseases, and lack of proper food, millions of children and other vulnerable people could die," said Martin Mogwanja, the U.N. humanitarian coordinator for Pakistan.
"We are confident that the world will not stand by and watch this happen."
