Pakistan Navy soldiers rescue stranded villagers from flooded areas near Sukkar in Pakistan's Sindh province on Friday. Stormy weather grounded helicopters carrying emergency supplies as the worst monsoon rains in decades brought more destruction to a nation already reeling from Islamist militant violence.

SUKKUR, Pakistan — More rain soaked flood-ravaged Pakistan on Saturday and even heavier downpours were forecast for coming days, deepening a crisis in which hard-line Islamists have rushed to fill gaps in the government's patchy response.

Pakistani officials estimate as many as 13 million people throughout the South Asian nation have been affected by the rising waters. About 1,500 people have died, most of them in the northwest, the hardest-hit region. Mass evacuations were under way in the southern province of Sindh after the Indus River rose there.

The intense flooding that began about two weeks ago has washed away roads, bridges and many communications lines, hampering rescue efforts. Incessant monsoon rains have grounded many helicopters trying to rescue people and ferry aid, including six choppers manned by U.S. troops on loan from Afghanistan.

The national government's response has appeared chaotic at times, and confidence in its 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 Friday in the northwest, but downpours in the evening and early Saturday again swelled rivers and streams. Pakistani meteorologist Farooq Dar said heavy rains in Afghanistan were expected to make things even worse over the next 36 hours as the bloated Kabul River surged into Pakistan's northwest.

That will likely mean more woes for Punjab and Sindh provinces as well, as new river torrents flow east and south.

Authorities have given varying tolls for the number of people among Pakistan's 175 million impacted by the floods. The United Nations said 4 million people had been affected.