With winter fast approaching, he said the number of survivors "exposed to the elements" could double if emergency shelter fails to be provided.
"They can't go into their houses. They're trapped. They don't have any shelter, so that problem's the biggest problem facing Pakistan," Khan told Britain's ITV television on last Sunday.
Asked if the international community could have done more to help, he replied: "I suppose if you see the response to the tsunami (last December 26) and compare it to this catastrophe, the response has been poor."
Pakistani President Pervez Musharraf and UN relief officials have called for helicopters, winter tents, blankets, food and medicine to help earthquake survivors, thousands of whom remain cut off in the Kashmiri mountains.
The powerful temblor injured 75,000 people and left another 3.3 million homeless in Pakistan, according to Pakistani estimates. Some 1,300 people also died on the Indian side of divided Kashmir.
Maleeha Lodhi, the Pakistani high commissioner (ambassador) in London, also speaking to ITV television, described the catastrophe as being of "epic proportions".
"Pakistan has never confronted a challenge of this kind and therefore, obviously, we are also very concerned that we have to act quickly and comprehensively to prevent a second wave of deaths," she said.
While US military helicopters have come over from Afghanistan to help, Lodhi said Islamabad was not prepared to accept India's armed forces on the Pakistani side of disputed Kashmir even to assist in the relief work.
"Much more" overseas aid is required to deal with the danger of sickness and foul weather, she said.
"The world community has to somehow find it within itself to respond quickly and more generously than it has," she said.