Tents, blankets and other badly needed supplies began flowing Wednesday to towns in the earthquake-stricken zone of Pakistani-controlled Kashmir, but the army had yet to reach many isolated villages. Pakistan's president, Gen. Pervez Musharraf, faced criticism and warnings of potential political trouble while expressing regret for delays in relief efforts.

Along twisting mountain roads, relief convoys wound slowly past rockslides and knots of desperate, hungry survivors, many of whom had walked out of their ruined villages after spending a fourth night in the cold. Helicopters that had been temporarily grounded by rain and hailstorms resumed shuttling supplies and evacuating injured victims of Saturday's quake, which killed an estimated 20,000 to 40,000 people in Pakistan's worst natural disaster.

At the same time, many victims expressed frustration and anger toward the government, and especially the army that keeps it in power, prompting some analysts here to make comparisons with the criticism leveled at the Bush administration following Hurricane Katrina.

In justifying his 1999 coup against an elected civilian government, Musharraf has repeatedly referred to the army as Pakistan's most competent and incorruptible institution, arguments he reiterated late last year when he broke a public pledge to step down as army chief of staff and govern as a civilian. The army's disorganized response to the disaster, some analysts said, could provide an opening for hard-line Islamic political parties and their associated social welfare groups, which have quickly and prominently swung into action.

During a three-hour drive Wednesday morning, a reporter traveling toward Islamabad from the badly damaged town of Rawalakot in Kashmir saw few military vehicles, none of which appeared to be carrying relief supplies. But the same road was crowded with private relief convoys, many belonging to the social service arm of Jamaat-e-Islami, Pakistan's largest and best-organized Islamic party.

"The government now effectively is the army and Musharraf, and when you see both bumbling, or not doing well anywhere, then it's a blot on the entire government and it's a blot on Musharraf," said Ayaz Amir, a columnist for the English-language newspaper Dawn. "What they like to say about it is that it is the only functioning institution in the state and when all else fails it's the army that holds everything together. . . . Here you have the one institution which failed above all is the army."

Musharraf acknowledged the slowness of the relief effort in a live television address Wednesday night, but said the government had done the best it could under the circumstances. He said landslides had cut off access to many of the hardest-hit areas and asserted that "any country" would have faced similar problems. He said the army had reopened key roads and was now moving quickly to aid survivors, opening field hospitals and dispatching search teams to remote areas.

"The easiest thing is to blame someone," he said, according to a translation by CNN. "I am very sorry for the delay but there was no other way."

Moreover, Musharraf and other military officials said, the army was badly hit by the earthquake, which killed an estimated 450 soldiers, injured 1,000 others and knocked out communications and other key facilities, including military hospitals. The army has long maintained a huge presence in the disputed Kashmir region and thus was particularly vulnerable, officials said.

As foreign governments offered help, Secretary of State Condoleezza Rice, on a tour of Central Asia, held talks with Musharraf and other officials during a two-hour visit to Islamabad, the capital.

The United States has dispatched 12 helicopters and other transport aircraft to Pakistan and has pledged an initial $50 million in relief funds. The Bush administration is assembling a task force to examine what more can be done to stabilize Pakistan in the longer term, she told reporters traveling with her.

"The devastation is quite extraordinary," Rice said. "The international community will have to be mobilized to help with ongoing rescue efforts as well as the long-term recovery and reconstruction." Stability in Pakistan, the only Islamic country with a nuclear weapon and the most crucial ally in tracking the elusive al Qaeda leadership, is critical to U.S. interests in South Asia.

"Relief material is moving in," said Jan Vandemoortele, the U.N. resident coordinator for Pakistan. "It is getting there. Roads are open now. They were blocked until very recently. We have several trucks that are all loaded and on the road now."

[Early Thursday, a brief 5.6-magnitude aftershock was felt in Islamabad and other areas, but there were no immediate reports of damage.]

Among the countries offering help was India, Pakistan's rival, which dispatched a plane to the capital filled with relief supplies on Wednesday. India and Pakistan have fought two wars over Kashmir, which is predominantly Muslim. About 1,400 people are thought to have died in the quake on the Indian side of Kashmir.

Despite the influx of aid, U.N. officials emphasized that far more would be needed and broadcast an appeal for $272 million to cover relief and recovery projects for the next six months. U.N. officials estimated that several million people had been made homeless.

Aid reaching the earthquake zone so far has focused on several larger towns such as Balakot and Muzaffarabad, the capital of Pakistani Kashmir, which was mostly destroyed. But even there, the slowness of the supply operation was provoking anger. In Muzaffarabad on Wednesday, survivors mobbed a relief convoy in a frenzied scramble for bottled water, blankets and biscuits, beating its drivers and forcing them to retreat to the safety of an army camp, the Associated Press reported.

The situation was more desperate for survivors in remote villages, many of which are hidden high on the sides of forested mountains and have yet to receive outside help. On the road from Rawalakot on Wednesday morning, some villagers had put up a banner pleading for help, and a girl who appeared to be about 12 raised her hand to her mouth to indicate she was hungry.

"The cargo moves to the cities on this road, but there is no assistance for us," said Guj Tal, 30, who was waiting with a group of survivors from his tiny settlement about a 30-minute walk from the road. "I've been standing here for tents and blankets. It was really cold last night. There were two blankets for 12 people."

Tal said he and his relatives were sleeping in the open because the earthquake had destroyed their home, killing his two younger brothers, 7 and 15, who were making tea in the kitchen.

"The government is not doing anything to provide relief to people," said Amanullah Khan, a prominent Kashmiri politician who favors independence from both India and Pakistan, quoted by the Reuters news agency. "People are angry and it is growing more and more every day."

One possible beneficiary of the popular anger, some analysts said, is Jamaat-e-Islami, which is ideologically linked to Egypt's Muslim Brotherhood as well as Hamas, the Palestinian militant group. The party has a charitable arm, Al-Khidmat Foundation, which operates numerous social welfare programs and has rushed to respond to the earthquake by organizing relief convoys, appealing for donations and providing medical help.

"These groups are better organized to provide welfare services than the government," said Hasan Rizvi, a political analyst and the author of several books on Pakistan's army. "This again will promote hard-liners and religious extremism in Pakistan."

Maj. Gen. Shaukat Sultan, the chief military spokesman, said the criticism of the army was unfair. "The Pakistani army was the first to receive the brunt of the quake," he said. Besides those killed, he added, "about 1,000 of our troops lay wounded with no -- I repeat, no -- medical facility in the area."

Sultan said that the army was rushing fresh troops to the earthquake zone but that "reconfiguration and movement of troops takes time, especially when you literally have no airborne facilities and roads are either clogged with traffic or blocked because of landslides."

Staff writer Robin Wright in Islamabad and special correspondent Kamran Khan in Karachi contributed to this report.

Saturday's quake left several million people homeless, U.N. officials have estimated. A Chinook helicopter takes off from Balakot, Pakistan, to rescue injured people in isolated villages and to deliver supplies. Landslides blocked many roads, so little aid has gotten through.Carrying their injured and dead, people by the hundreds have hiked from distant mountain villages to Balakot in hopes of finding food and other aid.