The United Nations says more than 4 million people were without shelter following three weeks of floods in Pakistan.
The UN had previously estimated about 2 million people were made homeless by the worst floods in the country's history.
The UN has launched an emergency appeal for $460 million in emergency aid, but as of August 18 had received pledges for just over half the amount.
Later today, UN Secretary-General Ban Ki-moon is to brief a special meeting of the General Assembly on his visit to Pakistan on August 22 and urge for more aid for flood victims.
U.S. Senator John Kerry, who is visiting Pakistan, on August 19 said the United States would increase its aid from $90 million to $150 million. The figure is expected to be announced at the General Assembly meeting in New York later on August 19.
Germany and Saudi Arabia have also announced new pledges of aid.
Up to 1,600 were killed in the floods which affected some 20 million people.
compiled from agency reports