CHAMAN, Pakistan - Afghans fleeing U.S.-led air attacks on their cities are streaming across the border into Pakistan, with 3,500 refugees arriving Friday, the United Nations said. Many described an increasingly chaotic journey.

Ron Redmond, spokesman for the U.N. High Commissioner for Refugees, said 3,500 people arrived in the Pakistani border town of Chaman early Friday, and the influx was continuing.

The flow of refugees appeared to be rising. Redmond said about 10,000 people crossed into the area last week.

"The situation was described by monitors as chaotic," Redmond said in Geneva. "People are arriving with no food or belongings. Some families have become separated."

Most of the refugees said they were fleeing heavy bombing this week in Kandahar, the southern Afghan city where the ruling Taliban have their headquarters. One, Amir Agha, 42, said he saw bodies lying in Kandahar's streets. He said people were dying in hospitals because doctors lacked the drugs to save them.

Thousands of refugees are stranded on the Afghan side of the border, prevented from getting into Pakistan, he said, by a border shutdown that permits only Afghans with valid documentation from crossing.

"They're chanting slogans against the Taliban," Agha said. He said some were clashing with Pakistani border guards.

Another refugee, Abdul Qayyum, 29, said thousands of Kandahar's residents had left.

"We are not coming here by choice," Qayyum said Friday after crossing into Chaman with his wife and three children. "We are helpless. We are poor. We don't have food, we don't have medicine and we cannot sleep in our own houses."

"We know we will lead a miserable life in Pakistan in tents," he said. "We have come here just to save our children."

Pakistan has said it will accept refugees but prefers that international aid agencies focus on helping displaced Afghans within their own country.

Farther north, hundreds of people were fleeing the eastern Afghan city of Jalalabad for crossings in and around the Khyber Pass, the rugged region that separates Pakistan from Afghanistan, according to local residents.

Samiullah, 50, a shop owner from Jalalabad who uses only one name, crossed into Pakistan with his wife, Zulekah, and their three children. He said they paid $25 each for eight-hour mule rides to the border area of Lindi Kodal.

"We didn't have anything to eat the whole way," he said. "It was a terrible journey, but we were lucky that we had money to pay those people."

He said the family saw hundreds of people fleeing _ most with little more than their clothing.

"They were in miserable condition. Most of them were women and children and old people," Samiullah said Thursday, hours after crossing.

Redmond said refugee arrivals were being hampered by changing rules at the Pakistani border. "It's erratic _ some days the border is open, some days it's closed."

The U.N. High Commissioner for Refugees agency was waiting for permission from Pakistani authorities to truck water and food to the new refugees, Redmond said.

UNHCR has said bureaucratic obstacles and security problems in Pakistan have slowed preparations for refugees from Afghanistan.

The agency said its worst-case scenario would involve accommodating 1.5 million new Afghan refugees.

President Bush ordered the attacks beginning Oct. 7 to root out Osama bin Laden and his al-Qaida network, blamed for the Sept. 11 terrorist attacks in the United States, and to punish Afghanistan's ruling Taliban, who harbor bin Laden.