SUKKUR, Pakistan (AP) — Stormy weather grounded helicopters carrying emergency supplies to Pakistan's flood-ravaged northwest Friday as the worst monsoon rains in decades brought more destruction to a nation already reeling from Islamist violence.

U.S. military personnel waiting to fly Chinooks to stranded communities in the upper reaches of the hard-hit Swat Valley were frustrated by the storms, which dumped more rain on a region where many thousands are living in tents or crammed into public buildings.

Over the last week, floods triggered by monsoon rains have spread from the northwest down Pakistan, killing around 1,500 people. They were faster and more destructive in the northwest, where waters were receding Friday. The floods were moving south along the River Indus, causing less damage and death but inundating hundreds of villages nevertheless.

Some 30,000 Pakistani soldiers are rebuilding bridges, delivering food and setting up relief camps in the northwest, 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.

The United Nations said 4 million people had been affected, 1.5 million severely, meaning their homes had been damaged or destroyed. Earlier, Nadim Ahmed, the head of the National Disaster Management Authority, said 12 million people had so far been affected by the floods and 650,000 houses destroyed. He did not elaborate.

The United Nations said the disaster was "on a par" with the 2005 Kashmir earthquake — which killed about 73,000 people — in terms of the numbers of people needing assistance and damage to infrastructure.

In a televised address to the nation, Prime Minister Raza Yousuf Gilani said it was the worst flooding in Pakistan's 63-year history.

Also helping out in the relief effort are Islamist charities, including the Falah-e-Insaniat Foundation, which Western officials believe is linked to Lashkar-e-Taiba, the group blamed for the 2008 Mumbai attacks. The group has been subject to a ban, but it has been challenged in court and patchily enforced.

Foundation head Hafiz Abdur Rauf said the assistance of the U.S. Army was welcome.

"This is a difficult situation for us. Every helping hand and donation is welcome," he said, adding that his group is running 12 medical facilities and providing cooked food for 100,000 people everyday. The foundation helped out after the Kashmir earthquake under a different name.

The government has come under criticism for not doing enough, especially since President Asif Ali Zardari chose to go ahead with a trip to Europe at the height of the crisis.

In the Sukkur area of Sindh in southern Pakistan, 70 villages had been flooded over the last 24 hours, the navy said.

"Floods killed our people, they have ruined our homes and even washed away the graves of our loved ones. Yet we are here without help from the government," said Mai Sahat, a 35-year-old women looking over a flooded landscape where her village used to be.

Saleh Farooqi, head of the Provincial Disaster Management Authority in Sindh, said authorities had evacuated about 200,000 people from areas where floodwaters could hit, but many more were still living in the danger zone.

"About 500,000 people living near the Indus River do not realize the gravity of the situation, and they do not know how fast the water is rushing to their areas," he said.

All helicopters currently stationed in the northwest were grounded because of poor weather, said Amal Masud, a spokeswoman for the National Disaster Management Authority.

About 85 U.S. military personnel are taking part in the relief activities along with six helicopters that were flown over from Afghanistan, where some 100,000 American troops are based battling the Taliban.

Specialist Joseph James usually flies Chinooks on combat missions in Afghanistan and was happy with his new mission.

"It just feels nicer helping people," he said at a Pakistani air base in Ghazi where biscuits and water were being loaded into choppers. "The first time we got up there, everybody was shaking our hand," said the 22-year-old from Union Star, Missouri.

The United States is unpopular in Pakistan, and Washington is hoping the relief missions will help improve its image.

The U.S. military carried out larger operations in the aftermath of the Kashmir quake, as it did in predominantly Muslim Indonesia after the 2004 tsunami. Those missions were credited with boosting Washington's reputation there.


Toosi contributed to this report from Ghazi.