SUKKUR (AFP) A senior UN envoy warned Wednesday that militants could exploit Pakistans worst humanitarian disaster as the government called on foreign donors to step up efforts to contain the crisis. Government has admitted being unable to cope with the scale of the crisis and an outpouring of rage from survivors and the political opposition is compounding pressure on President Asif Ali Zardari. Religious charities have filled some of the vacuum, leading to warnings within the United States about rising extremism in the country. UN aid envoy for Pakistan, Jean-Maurice Ripert, also warned that armed militants could take advantage of the disaster. The peoples misery can always be exploited by those who have political or militant aims, he was quoted as saying by French newspaper Le Monde, describing the floods as the worst natural disaster the country has known. The Taliban have called on the government to turn down all foreign aid for the victims and offered to cough up 20 million dollars on their own, without any indication it could pay. We condemn American and other foreign aid and believe that it will lead to subjugation. Our jihad against America will continue, spokesman Azam Tariq told AFP by telephone.