With monsoon rains continuing in Pakistan on Wednesday and water-borne diseases reported spreading, international relief officials said the pace of aid donations was still not sufficient to deal with what might be the nation's worst disaster. 'The scale of the response is still not commensurate with the scale of the disaster of almost unprecedented magnitude,' said Martin Nesirky, the spokesman for the U.N. secretary-general, Ban Ki-moon, reading a statement from the humanitarian affairs office. 'This is a catastrophe that continues to unfold.' Since the weekend the pace of pledges to the United Nations' $460 million appeal has accelerated, Nesirky said, but it remains short of its target. 'The funding response to the floods is improving, but much more is needed,' he said. 'The effort must be sustained in the days and weeks ahead in order to have the resources to reach the people who desperately need help.' The United Nations began an appeal Aug. 11 for $460 million to provide immediate aid to flood victims. By Wednesday, nations, organizations and individuals had sent $231 million, and had pledged an additional $40 million. The United States was by far the largest single donor, with $82 million, according to U.N. figures, with Australia the next largest donor at $26.6 million. The United States said its total contributions amounted to $90 million, including helicopters, boats and temporary bridges, according to the State Department. Britain has sent more than $40 million and the European Union said it would double its aid to more than $90 million. Although the disaster has fallen in the Muslim holy month of Ramadan, when charity is considered a duty, Muslim states have donated virtually nothing via the United Nations and relatively small sums on their own. Turkey was the largest such donor, with more than $11 million, and Kuwait donated $5 million, U.N. figures show. Saudi Arabia has pledged more than $80 million, but U.N. records indicate none of it has been delivered. The United Nations and the aid agencies through which it works have thus far delivered food to nearly 800,000 people, have helped get clean water to at least 1.4 million and have provided shelter to nearly 1 million. Medical stocks covering the potential health needs of 1.8 million people have also been provided. 'Unfortunately, this is only a fraction of what we need to do,' said Martin Mogwanja, the U.N. humanitarian coordinator for Pakistan. 