Authorities have evacuated thousands of Pakistanis living along expanding rivers as forecasts predicted even more heavy rain could deepen the country's flood crisis.
As the prime minister appealed for national solidarity, hard-line Islamists rushed to fill in the gaps in the government's aid effort.
Pakistani officials estimate as many as 13 million people throughout the South Asian nation have been affected by the worst flooding in the country's 63-year history, though the United Nations, apparently using different metrics, has put the number at roughly four million. About 1,500 people have died, most of them in the north west, the hardest-hit region.
The intense deluge that began about two weeks ago has washed away roads, bridges and many communications lines, hampering rescue efforts staged by aid organisations and the government. Incessant monsoon rains have grounded many helicopters trying to rescue people and ferry aid, including six choppers manned by US troops on loan from Afghanistan.
Confidence in the national government's ability to cope has been shaken by the decision of President Asif Ali Zardari to visit France and England amid the crisis.
Floodwaters receded somewhat on Friday in the north west, but downpours in the evening and early on Saturday again swelled rivers and streams. Pakistani meteorologist Farooq Dar said heavy rains in Afghanistan were expected to make things even worse into Sunday as the bloated Kabul River surged into Pakistan's north west.
That will likely mean more woes for Punjab and Sindh provinces as well, as new river torrents flow east and south.
Pakistan's military said it had rescued more than 100,000 people from flood-affected areas, while 568 army boats and 31 helicopters were being used for the rescue operation. The army was also providing food and tents to the survivors, an army statement said.
Some 30,000 Pakistani soldiers are rebuilding bridges, delivering food and setting up relief camps in the north west, which is the main battleground in the fight against al Qaida and the Taliban. Foreign countries and the United Nations have donated millions of dollars to the aid effort.
Nato said in a statement that Pakistan had asked for help dealing with the crisis and said it would help co ordinate assistance offered by members and partner nations, including aid transport.